[Transcript] – Everything You’ve Ever Wanted to Know About Blood Sugar & Glucose Monitoring, But Were Afraid To Ask Or Didn’t Realize, With Casey Means Of Levels.

Affiliate Disclosure


From podcast: https://bengreenfieldlife.com/podcast/glucose/

[00:00:00] Introduction

[00:00:45] Podcast Sponsors

[00:04:14] Podcast and Guest Intro

[00:08:52] Where to wear the CGM for accuracy so it doesn't hinder daily activities

[00:11:52] How exactly does the CGM gather sugar data?

[00:14:32] Differences in accuracy and measurement between a typical finger prick using blood and a continuous blood glucose monitor? When is it necessary to recalibrate a CGM?…

[00:18:41] Are there any preferred brands or any brand considered to be a gold standard?

[00:22:06] Are there any concerns about dirty electricity or EMF exposure when using a CGM?

[00:24:53] What kind of things might cause the sensors to fail or give an inaccurate reading (e.g., could things like heat, cold, etc. cause inaccurate sensor readings)?

[00:31:33] Do infrared lights, PEMF, or vibration platforms cause sensors to fail?

[00:35:00] If you don’t have diabetes, you can still get the sensor and the app, but does insurance cover it? If not, what is the approximate cost?

[00:36:33] Podcast Sponsors

[00:40:26] Any tips for placement of a CGM on the body and how to ensure that it sticks for as long as possible?

[00:43:36] What is a good average blood glucose level? How much should it rise after a meal, and how long should it take for blood glucose to return to baseline?…

[00:51:11] Adaptive glucose sparing

[00:55:40] What are the most interesting experiments people have been running on levels with their blood sugar, and what have been some of the more surprising or unexpected results from those experiments?

[00:59:07] Does dairy spike blood glucose?

[01:00:24] What about other dairy substitutes like rice milk, oat milk, and almond milk?

[01:06:25] From a supplementation, lifestyle, or biohacking standpoint, what are some lesser-known ways to control blood glucose?

[01:14:46] In the future, based on what is in the interstitial fluid, could a CGM eventually measure cortisol, inflammatory markers, etc.?

[01:18:11] End of Podcast

Ben:  My name is Ben Greenfield. And, on this episode of the Ben Greenfield Life podcast.

Casey:  So, we're all in this 110 to 120 as your peak post-meal glucose. I like to stay about between 70 and 90 in between meals, like resting during the day, and not really go above 120 after meals. And, I like to go up and come down within two hours. And, that will pretty much make me feel my best.

Ben:  Faith, family, fitness, health, performance, nutrition, longevity, ancestral living, biohacking, and a whole lot more. Welcome to the show.

Alright, so I just got back from a trip. My Levels continuous blood glucose monitor is waiting for me. I slapped it on, it's on the back of my arm right now. I've been using this thing for two years. Total game changer. I'll put it on for about two weeks and then take a break for a month or two. Some people wear all year round, but it gives you real-time feedback on your diet, or your lifestyle, or your exercise, anything by using what's called the continuous glucose monitor.

Now, poor glucose control is associated with a number of chronic conditions, not just diabetes, but also Alzheimer's and heart disease, and stroke, even affects your day-to-day energy levels, your ability to control weight, your sexual function. So, I started tracking my own glucose to learn more about not only what I should and shouldn't be eating, but how I should train, other things that drop my blood glucose, things that raise my blood glucose. When I started as a Levels member, I thought I understand my metabolic health pretty well, it turns out, like most people, I didn't have that great of an idea about how some foods surprisingly were affecting me like steak spikes my blood sugar, cold bath decreases it. Green beans spike my blood sugar. Not so much with oatmeal. It's super weird. And, everybody's different, which is why you really don't know unless you test. What you read in a magazine that's going to spike or control your blood sugar is not necessarily what's accurate for you personally.

So, if you want to try one of these continuous glucose monitors also known as the CGM, you go to levels.link/Ben. They got a really well-researched in-depth blog I recommend checking out if you're just looking to learn more about topics like metabolic health, longevity, and nutrition. Very well written, but levels.link/Ben is where you can actually get one of these continuous glucose monitors for yourself.

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Unless you've been hiding under a rock or something, you probably have heard about this thing, this trend in health called CGM. CGM stands for continuous glucose monitoring. Continuous glucose monitoring. Like you might have seen me sometimes wearing a patch on my arm, usually I put on the back of my arm even though I'll ask today's guests if that's a decent place to put her if I'm totally messing up. But anyways, it tracks my blood glucose 24/7 all the time. You may have been to the pharmacy and seen those little blood glucose pricks that you can get where you prick your finger and you bleed onto the little thing. This is just doing that but all the time, even though there might be some subtle nuances or differences, which I will also ask my guest about today. 

They're super useful because even if even if you're not diabetic, I think it's no secret that paying attention to your blood sugar is one of the most important things you can do for your health. As a matter of fact, I'm convinced that paying attention to that, paying attention to your inflammation levels, and paying attention to what's called your heart rate variability are possibly three of the best things to track when it comes to keeping your finger on the pulse of your health.

There's so many benefits to tracking blood sugar, and so much I've learned over the past few years, but I haven't ever really done a big podcast on all of the nitty gritty questions that I have about continuous glucose monitors. For example, like I mentioned earlier, where do you put them? Like your arm, your stomach? What are some surprising things that you might not know that might spike your blood sugar? Strangely enough for me, one thing I found was green beans. Then it turns out I did a food allergy test, I'm actually allergic to green beans, which is weird because that's a slow-carb, low-carb food. Are there differences in accuracy between these different brands like the Dexcom or the FreeStyle? Are there other things these things could potentially track besides blood glucose? What are some reasons that people who are healthy might still have high glycemic variability? When is blood sugar going too high, I don't know, maybe from a sauna or an exercise session not an issue? And, what do you need to be concerned about it? How soon should it come back down? Just so many questions.

So, I decide I want to get somebody on the show who I could geek out on this stuff with. Fortunately, she's a doctor. I'm not a doctor, I just have the T-shirt. Her name is Casey Means. And, you may have heard of her before if you have looked into CGMs because she's actually the chief medical officer of one of the top metabolic health tracking companies out there called Levels. Levels is this company that has an app that will allow you to go way beyond whatever the native plain Jane no-frills app was that came with your continuous glucose monitor, and do a ton of other stuff like run tests and get a lot more insight into glycemic variability and learn a lot more about your body. It's a pretty cool app. I have really, really enjoyed using it, learned a ton from it. Casey is the person who's the mastermind behind this in terms of advising Levels. She guest lectures at Stanford. She's associate editor of the International Journal Disease Reversal and Prevention. And, she lives her life through the lens of trying to reverse the epidemic of preventable chronic disease, in many cases by helping people control their blood sugar. And, she's well-published, well-respected, and very well-known for being an expert in the whole continuous glucose monitoring space.

So, Casey, welcome to the show.

Casey:  Thank you so much, Ben. I am so excited to have this conversation with you.

Ben:  Yeah, it should be pretty cool. And listen, I know because I've heard you on other podcasts and probably a lot of people are aware of this. I don't think that we have to spend an hour on this podcast telling people that controlling your blood sugar is a good idea or tracking your blood sugar might be handy for you to do. We could, but I want to dig into this stuff that's selfishly enough. I want to know about that maybe isn't asked enough from a blood sugar standpoint if you're game. Is that cool?

Casey:  Absolutely.

Ben:  Okay, alright. So, I guess my first question is, and this is alluding to something I already mention in the introduction, but are you wearing one of these things right now?

Casey:  Right at this very second, I don't have one on because it actually expired yesterday, so I have to put a new one on today.

Ben:  If I could explain this to folks is like a sensory, slap it on your body and it will stay active for a certain period of time. But, I'll wear mine and then take it off. And, after I've learned a whole bunch for a couple of weeks, put it back on a couple of months later, or perhaps when I'm having weird energy levels or weird sleep, I'll put it on just to see what's going on with my blood sugar.

But, if you were wearing one Casey, where would you stick it for the ideal combination of accuracy and ability to engage in your daily functions like workouts and things like that?

Casey:  I personally love it on the back of my upper arm. So, this is a very standard place that you'll see a lot of people wearing it like when you're just walking down the street. And so, the reason I like it on the back of my arm is for a few reasons; I think just in terms of where the options are. So, for the FreeStyle Libre, which is one of the main types of sensors. There's three main companies that make these sensors, which is Abbott, which is the FreeStyle Libre, there's Dexcom that makes the G6 and there's Medtronic. The two sensors that Levels members use are the FreeStyle Libre and the Dexcom G6. For the FreeStyle Libre, it's approved for the back of the upper arm. So, that's really the place that they recommend wearing it. And, for the Dexcom G6, they actually say that you can wear it on your upper arm, your abdomen, or your upper butt basically. So, on your haunches, which I have not heard of very many people doing, but you can. And, the upper arm for me, I mean frankly one of the reasons is that I kind of like showing it off. I think it looks cool.

Ben:  Yeah, it is kind of a conversation starter, isn't it?

Casey:  It's such a conversation starter. And, I think it's becoming more and more a symbol of people similar to wearing other wearables like an Oura Ring or an Apple Watch. It's a symbol of caring about your health and showing to people that that is something that you value. And, I think it's becoming a little bit of a fashion symbol in a way. And, of course, on top of the CGM, we have the Levels performance cover, which is a great cover that makes it essentially waterproof and sweat proof and you're not going to catch it on a doorway as you're walking through and peel your sensor off, which can sometimes happen if you're not wearing the sticker.

Ben:  Yeah.

Casey:  Just in terms of the upper arm, there's a lot of ways, I think to do it in a way that's most accurate and comfortable. I like to basically almost pull down on the area behind my tricep. So, we're talking about back of the arm about 2 inches below the armpit crease. I kind of pull down on the fleshy area behind the tricep and try and get it in as much sort of fleshy or fatty tissue as possible. So, not right into the muscle if I can avoid it. For people who are super ripped, there sometimes isn't a lot of that tissue, but as much as you can kind of get it in the fleshy or fattier tissue and not right in the muscle belly, that's going to be better from both the perspective of pain but also I think for consistency of your readings.

Ben:  Okay. Yeah, I've run into that. I don't have a ton of fat on the back of my arm but that's where I tend to put it. I find that just seems to stick to best there and stay the longest there. When you slap the sensor on, you press the button and this teeny, teeny tiny like smaller than a hair-like needle goes deep into the tissue.

How is it measuring in terms of the location of the sugar, if that makes sense, versus if I were just prick my finger and bleed onto one of those little strips? Is it measuring it from the blood or is it measuring it from inside the muscle? Or, can you explain in layperson's terms how exactly it's gathering that sugar data? 

Casey:  Yeah, absolutely. So, the way it works, like you said, there's this little filament that goes into the skin. You actually do apply this with a little device and applicator that does have a needle, and all that needle is doing is actually pushing this dental floss-type material under the skin. And, that needle immediately retracts, so there's no needle that actually stays in the body, nothing rigid, which I think is definitely reassuring to know that there's not some rigid thing that's sticking in there. But, that's sticking out of the bottom of the plastic sensor that's affixed to the outside of your skin. So, it's almost like a big thumbtack, but the tack part is actually flexible on that filament that goes under the skin, which for the FreeStyle Libre is actually 4 millimeters long. So, it is so, so, so, so tiny. The Dexcom G6 filament is a bit longer. I don't know the exact length, but probably about I would say a centimeter and a half or so. So, it's a little bit deeper. 

That filament that's under the skin is sitting in what's called the interstitial fluid, so not actually measuring blood, not in a blood vessel, it's in this sort of space between cells. And, the filament is coated with an enzyme called glucose oxidase that's actually doing a chemical reaction like an actual lab test in your arm automatically every 15 minutes or so and sending that information to your smartphone. And so, what happens is that basically, glucose reacts with this enzyme that's coding the filament and actually converts to hydrogen peroxide, which creates an electrical signal that's then basically registered as a glucose concentration.

And, I think one of the reasons I like to not get it right in the muscle, if I can avoid it, is that I do think that — I can't verify this, but this is just my hunch from wearing one for about three years that sometimes if you get it right in the muscle, there can maybe be some more bleeding and inside very small amount. And then, that can maybe interfere with some of the signals. So, just getting it into anything that's a bit flashier and really getting into skin subcutaneous tissue. So, things can be different if you're sensor to sensor. Each sensor can read a little bit differently. And, different placement, you can sometimes see differences. So, I just try and keep it as consistent as possible in terms of my placement sensor to sensor, not kind of move it around my arm. Yeah.

Ben:  Okay.

Now, some of these sensors, like when you open up the app, it says you could calibrate, which means that you can take your blood glucose reading from your fingertip and match it up to what it has on the sensor, I suppose. But, if your fingertip is measuring your blood glucose and the sensor is measuring more the glucose in this interstitial fluid, are they going to be the same? 

The reason I asked this is that from what I understand, glucose goes from your blood vessels in your capillaries first and then into your interstitial fluid. So technically, if it was high in the blood, it might still be low in the interstitial fluid or vice versa. So, why is it that you'd calibrate by using the blood? Does that make sense?

Casey:  Totally. Yeah. So, prior to CGMs being these devices that so many people with diabetes are using and now that people are using more for the general wellness market, people were pricking their fingers and that is actually using similar technology of glucose oxidase reactions but using blood to do so. And, like you said, once you digest carbohydrates, they go into your bloodstream. And then, from the bloodstream, they will then sort of seep into the interstitial fluid. And, the concentrations between the interstitial fluid and the blood are very, very similar but it takes time for it to get out of the blood. So, you can think of the interstitial fluid readings like on a CGM as just phase shifted, somewhere between maybe 5 to 15 minutes into the future. For instance, you just ate a high-carb meal and you have a quickly changing glucose in the bloodstream, that's where you might see quite a big difference between what's in your blood and what's in your interstitial fluid because it's going up, it's changing very, very quickly.

If you're just fasting and your blood sugar has been the same for an hour, then your interstitial fluid should be pretty similar to what's in the blood. So, things that can make the difference between what's in the blood and what's in the interstitium different is if glucose is changing rapidly, so then you might see what's on your CGM essentially maybe 15 minutes delayed from what's in your blood. So, if you're just actively pricking your finger and checking your sensor after a meal, the other things that can make it inaccurate is actually just the first day of the sensor. So, both the FreeStyle Libre and the Dexcom, the manufacturers mentioned that day one can be a little bit off. So, I don't actually put much stock in my readings in the first 24 to 36 hours. I will take stock in the delta between the beginning of the meal and after the meal, but the actual raw number, I don't really take much stock into that until about 24 to 36 hours when I know that it's going to be a bit more precise.

And, all the sensors are factory calibrated, so none of them actually require calibration, meaning that for them to be accurate, you don't actually have to prick your finger and put that into the app for the CGM to calibrate it. However, the Dexcom G6 has the functionality to allow you to do that, which means that you can take your little finger prick glucometer, prick your finger, put that into the Dexcom G6 app and it will actually essentially adjust what your CGM readings are. Again, that's not required for it to work properly, but it may make the accuracy a little bit better. 

But, the companies they've both studied basically what is the level of inaccuracy in these compared to blood. And, for both the FreeStyle Libre and the Dexcom, it's about 9% difference from blood on average, which means that if you're doing gold standard which is a venous plasma glucose measurement compared to CGM readings, it's a 9% MARD, which is mean absolute relative difference for both devices, which they were able to get FDA approval with that. And, that's pretty standard across wearables and that's good enough essentially for someone with diabetes to do things like manage insulin. So, I think just knowing that there are any tool is going to have some inaccuracy and 9% is pretty reasonable I would say.

Ben:  Okay, got it.

So, do you think that out of the Dexcom versus the FreeStyle versus the Medtronic one is the best? Obviously, there's differences between all of them but is one just considered gold standard?

Casey: There really isn't a reputation of one being the gold standard. I'd say in terms of market share and what customers tend to really like, I would say the FreeStyle Libre and the Dexcom G6 are the ones that I turn to the most. But, to be honest, so I have access to both. Of course, being part of Levels, and I honestly flip-flop back and forth between the two of them. 

So, the FreeStyle Libre, it is using what's called near-field communication, which means that you take your phone and you actually hold it up to the sensor and scan it to transfer the data from the sensor to the phone. And then, the Dexcom G6 is Bluetooth, so it actually just streams straight to your phone.

So, one thing, for instance, if I'm going on a wilderness trip or something like that and I really don't want to look at my screen very often and I don't want to be kind of interfacing with a device, I'll actually wear the Dexcom G6 because I know it's just going to stream the data straight to my phone. And, that's awesome. I don't have to basically interact with the phone as much, I could just look at the end of the day and see all the data. On the flip side, if I'm in the real world and not backpacking or something like that, I actually get a lot of benefit from scanning the phone to my sensor because it actually keeps me almost more in touch with this process, and it keeps me more thinking about glucose throughout the day.

Ben:  Yeah.

Casey:  And so, I actually like the process of scanning. You only have to do it once every eight hours. So, it really depends on the person and what you're looking for. But, both the FreeStyle Libre and the Dexcom I find to be very, very accurate compared to my blood glucose on my finger pricks. I will say the FreeStyle Libre tends to run low and the Dexcom tends to run high. Again, it's kind of anecdotal, but we obviously have seen a lot of members and gotten a lot of support emails from members and that is the trend that we see. Let's say I prick my finger and it's 85 milligrams deciliter, my FreeStyle Libre will often be reading 70 or 72 versus if I'm pricking my finger and it's 85 and I'm wearing a Dexcom G6, it'll often be reading 95 or 100. 

And so, I just know that. I think that you just have to know that there is going to be this slight difference like there is some baseline level of inaccuracy. And, I think that what that gets to is knowing that the main purpose of these tools is to understand trends throughout the day and the delta between pre-meal and post-meal. Those things tend to be fairly accurate. If I go up 50 points after breakfast, whether I'm with the FreeStyle Libre or the Dexcom, it's going to give me that same information.

Ben:  I totally get what you're saying. You're looking for a pattern either way. If it goes up, it goes up. If it goes down, it goes down. It might not be the exact number that's as accurate as you want it to be, but as long as you're able to pay attention to trends, you pretty much know what's going on, whatever. This cold shower made it go down and that meal with a steak and potatoes or whatever made it go up. So, yeah, I totally get what you're saying.

Now, regarding the difference between the sensors, one thing that I'm often asked about is because you're wearing this piece of electricity on your body all day long, whether people who are electro hypersensitive or concerned about dirty electricity or anything like that need to pay attention to. And, there's very little data out there about this. I found one YouTube video where someone was actually using one of those scanners to test the EMF levels of a Dexcom G6. Now, I'll link to it. If folks go to BenGreenfieldLife.com/glucose, that's we're I'm going to put the shownotes. And, I'll show you that video. 

And, what you're looking for ideally from a health standpoint is you want levels, if you're measuring in milliwatts per meter squared, which is the gold standard would be less than 1. And, that video, it was half that, it was really low. And then a lot of these things will use what's called a low radio frequency emission, meaning like a cell phone will put out 100 milliwatts, and any of these glucose testers, at least the ones I could find like the Dexcom and the FreeStyle, they're on average 4,000 to 5,000 times weaker than that. So, I mean, it doesn't even touch the equivalent of having a cell phone and even a cell phone in airplane mode in your pocket. So, I don't think that's something people need to be concerned about. But, have you ever thought about that or do you have any additional ideas in terms of the EMF dirty electricity piece?

Casey:  Just like you said, it is very understudied. I have dug deep into this like you have and have really mostly found what you're talking about which is blog posts of people testing this thing on their own YouTube videos, things like that. I came across I think what was the same source that you were talking about, which is the Dexcom, it was 4,000 times less than a cell phone call or something like that. I have no idea if that is accurate, but I'm hoping that it is. And, I think someone should do that study. I think it'd be fascinating. Anecdotally, I did go to my acupuncturist for some back pain a couple years ago and it was on my left side where my sensor was and he said something about how like, “I think you should think about the fact that you were in the sensor on your arm and it could be impacting your energy flow through this part of your body.” And so, that's always stuck with me of like, “Okay, this is a device in your body. Your body responds to something that is obviously in it,” but that type of study has not been done in a formal way.

Ben:  Yeah, I'm not concerned at all with the values. Again, if you own a phone, even if your phone is in airplane mode, you're getting exposed to a lot more from that alone. So, I wouldn't be as concerned about that.

But, it was kind of related to another question I wanted to ask you because look, I won't beat her on the bush here. I have a Dexcom and I've been using the Dexcom for six weeks. I switched from the FreeStyle Libre to the Dexcom. So far, I've had three transmitters fail. I've got no data over six weeks, aside from the very first day I had the second one on because they keep having to send me replacements. And so, I am just racking my brain around what would cause a sensor or a transmitter to repeatedly fail. Is it because I wear it in the sauna? Is it because I've got a pulsed electromagnetic field therapy thing that'll do therapy on sometimes? Is it some in the water in my house because the same thing has happened to another guy who works with me at my house? He's got Dexcom. His has failed twice in the past few weeks. So, I'm curious, what will cause a transmitter or sensor to fail so much? Is it something that they're getting exposed to do you think?

Casey:  I think it's possible. So, one thing to know is that the operating temperature of these devices is 50 degrees Fahrenheit to 113 degrees Fahrenheit. And so, if you're going far above that, which of course you are in a sauna or a cold plunge, it's going to go outside the range of the operating temperature. And so, that could very well be leading to a sensor issue.

There's a lot of other things as well. I think that one thing I've noticed, again, this is my own personal experience, not something that's in their official documentation, but if I put the sensor in a place where it happens to bleed more — so, every once in a while, I'll apply a sensor and I just some blood will leak around the sensor. This is very rare and definitely don't want to put people off from these. They typically are totally painless. You don't feel it going on and there's no blood. But, every once in a while, I mean, I've worn probably 100 of these at this point, there will be a little bit of blood that comes out of the center of the FreeStyle Libre or around the sensor if it's the Dexcom. And, I've noticed that when that happens, often the sensor fails. And, I think it's because the blood is coating the filament inside and it can't do the reading. 

And so, that is why I've become a bit more careful and precise about where I put the sensor and how I apply it. So, one tiny tip with the Dexcom is that the filament, when you take the sensor off, you can see that the filament goes at about a 45-degree angle out of the bottom. The FreeStyle Libre, the filament comes out at 90 degrees from the sensor. The Dexcom G6 comes out at about 45 degrees from the sensor. So, I make sure to apply the Dexcom G6 in a way that I know the filament is going to be going parallel to the long dimension of my arm and not sideways because if it's sideways, I'm assuming it's going to hit the muscle more.

Ben:  Okay, yeah.

Casey:  So, that's one thing. And, I think that when you hit the muscle, it does bleed more. And so, that's one thing I really try and avoid applying in a way that it's going. And, it's actually one thing you could try, Ben, is trying the butt where there may be a little bit more tissue.

Ben:  Yeah, that's a good point. I haven't tried alternate locations yet.

Casey:  One other thing to mention though is that a couple times my sensors has failed is when I was on an extended fast. So, when I was doing a five-day fast a couple years ago and my blood glucose obviously went down during the fast and my FreeStyle Libre was reading in the 40s, of course, my finger prick glucose was still in the mid-60s and I was asymptomatic so I wasn't too worried about it. But, once it started hitting the 40s regularly on the FreeStyle Libre — and again, the FreeStyle Libre tends to skew low especially if your blood sugar is actually low at the time. So, if you look at the accuracy curve for the Freestyle Libre, it's most accurate around the 80 to 200 milligram per deciliter range if your blood glucose is actually that. When you get into the extremes of the low, if your blood sugar is actually below 80, the sensor is going to start to get more inaccurate like that difference between blood and sensor is greater. 

So, if you're in a fast and your glucose actually is low in your blood, it could look even more inaccurate on the sensor. So, the sensor is reading the 40s and then it just stopped basically. And, I think the sensor probably has some sort of algorithm built in that basically says if it's reading values that are essentially incompatible with life, it's probably broken and it just stops itself. So, that's happened to me now on too fast or my blood sugar actually did go low. The sensor read it even lower and then it stopped.

Ben:  Yeah. Well, for you, what would really low be, just curiosity?

Casey:  Like in my actual capillary glucose or in interstitial fluid?

Ben:  I guess in the interstitial fluid that the sensor is reading.

Casey:  Like 60s.

Ben:  Okay, that's not super low.

Casey:  Yeah, yeah, I would say because I don't do full keto all the time. And so, I would say that my baseline glucose —

Ben:  What? You sinner.

Casey:  I know. Gosh, but I would say my glucose, generally, if I'm finger pricking during the day in between meals, would be around 72 to 85 or so, and then their sensor could be reading high 60s. Or, it could be a sensor that's super accurate and actually reading within 1 or 2 milligrams deciliter of the blood. But, that's where I tend to sit during the day. And so, the sensor could read, if it's a FreeStyle Libre, between high 60s and 80s.

Ben:  Do you think there's that much of a difference between sitting and standing by the way? Have you noticed that?

Casey:  I think so. I mean, I think when I'm working at my standing desk and I'm always moving my feet around, I've always got music on my headphones, I do think it keeps things just a bit more stable during the day. When you're sitting all day, there's no real glucose sink. Muscle is the most incredible glucose sink, and if you're using it even marginally, even just gently walking or bouncing around on your feet a little bit of your standing desk, you're activating huge muscle groups and they all take up glucose. So, I think any even marginal amount of movement makes a big difference.

Ben:  I agree. Mine is always consistently lower when I'm standing. Of course, when I'm walking on my new desk treadmill or I've got a little under-the-desk little bicycle type of thing, anytime I'm doing anything like that, it's lower, which seems intuitive. But, even just something as simple as standing instead of sitting actually does make a bigger difference than I would have thought. It's on average about five points lower if I'm standing versus sitting. So, it's pretty significant.

Okay. So, the other quick thing that I wanted to mention is we're talking about sensors failing. If you don't know the answer to this, that's fine, but this whole idea of these biohacks that produce electricity like infrared lights or pulsed electromagnetic field therapy, vibration platforms, things like that, have you ever come across anything that would, for sure, cause a sensor to fail that you know of?

Casey:  Not yet. Have not come across that. but, I bet we just launched a few months ago and so we're going to get a lot more people in the program and I would be so curious if this stuff starts coming up as the volume gets higher.

Ben:  Yeah. What do you mean you just launched a couple of months ago?

Casey:  We were in a closed beta for about two years. So, we were basically refining the product, growing operations, and then this summer, we've sort of more publicly launched. And so, anyone can come and get the product. And so, we'll just start to pick up more of these things as more people use the product and try different biohacks and experiments out. 

But, one thing we have seen and definitely have heard about is this idea of interfering substances with the sensors. And, the manufacturers talk about this, but there are a few medicines and supplements that are known to actually interfere with the chemical reaction on the sensor. So, the big ones are vitamin C and salicylic acid. So, what's in aspirin.

Ben:  Okay.

Casey:  And, it's dose-dependent. And, when you look at the research, it really seems like you have to be taking very high doses of these things for it to be a problem.

Ben:  Wait, I don't understand. What would they do exactly?

Casey:  Well, with vitamin C, for instance, there is some thought that it actually interferes with like the glucose oxidase enzyme.

Ben:  Oh, weird. Okay.

Casey:  And so, it actually will read much higher. So, people have reported being in the 300s if they take like 2 grams of vitamin C.

Ben:  Oh, wow.

Casey:  So, this would be relevant to someone and probably relevant to your audience like people who are doing an IV type vitamin C therapy or taking just a high oral dose. If your glucose goes up to 300 or 400, that might be why. So, salicylic acid is like aspirin and some skin care products have it that above about 650 milligrams, and the average pill is usually 325-milligram aspirin. So, if you're stacking these doses and taking a lot, it could affect the sensor. 

And then, hydroxyurea is another one that is thought to potentially impact the readings. And then, Tylenol used to have an issue with the sensors above about 1,000 milligrams. But now, both manufacturers advertise that there is no more interference with Tylenol. But, something to just keep in mind in case someone's on post-surgery or something and taking a lot of it and if they see the readings. But certainly, salicylic acid and vitamin C at high doses may affect the sensor and actually dehydration. If someone is really dehydrated, it can lead to either elevated or low reading. So, just want to make sure that you're hydrated.

Ben:  Okay. And hydroxyurea, that's a pharmaceutical drug, right?

Casey:  Hydroxyurea, you'd have to get through a prescription. 

Ben:  Okay.

Casey:  Yeah. It treats cancer.

Ben:  Okay, got it.

And, by the way, you mentioned that you had been in closed beta and now you guys at Levels are letting other people in. But, I should clarify because I think I understand the answer to this but if you don't have diabetes or chronic disease related to blood sugar, you can still get a sensor and get the app, but it's just that it's out of pocket and the insurance won't cover it. Is that correct?

Casey:  That's right. Yeah. And, Levels right now is actually exclusively a wellness product. So, it's not actually intended for any disease management or even disease prevention, it's meant for people who are trying to live their healthiest lives, trying to understand their bodies better to basically have this incredible data stream that helps them understand really for the first time how food is affecting their health in real-time and in a closed loop biofeedback way. 

And so, what Levels has done is take what was traditionally exclusively a medical device only used in the clinical setting and brought this to a mainstream sort of consumer audience of people who are optimizers or are interested in general health and wellness. Because of course, there's this huge, huge desire, not only amongst people who are interested in quantified self or wearables, but just generally people who have been struggling with trying to find the right diet for them, figure out how exercise affects their health, how sleep deprivation and stress affect their health to really be able to have extra granularity into that. So, yes, the people who are using Levels are people that actually do not have a clinical diagnosis and are using this for wellness purposes.

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Alright. So, whole-body wellness is obviously a huge part of my life. I'm always looking for new ways to make feeling great, be easier. And, one of my non-negotiables is my daily dose of red-light therapy. For years now, I've been using Joovv light therapy devices to do that all year long. I love it because they're non-invasive, they're simple to use, no hassle with complex monitors and cables, and shoving stuff in the orifices. You just flip them on. They can boost cellular energy. They can heal damaged cells under oxidative stress. There's many other clinically proven benefits to red-light therapy. Even testosterone production for guys. It's pretty crazy. 

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One other question regarding the logistics of this, then I want to ask you question about numbers and stuff. But, you talk about putting it on the back of the arm or for me, I guess now my butt, the package, when I get my Levels package, just got these little black stickers. It's almost like Kinesio tape, but it's in the shape of the sensor, whether it's the Dexcom or the FreeStyle and you slap it over there, you think that's enough to keep it on or are there other tips that you have for keeping it stuck to the skin, whether it'd be some kind of adhesive or glue or anything along those lines that you found that people really benefit from in terms of the stickiness?

Casey:  Great question. So, what you're talking about these patches and these stickers, these are the Levels performance covers. And so, these are intended to go over the sensor to make them more waterproof, more sweatproof, and again, prevent them from being dislodged. The one that always happens is when you're walking through a doorway and you catch your arm and it just peels your sensor off, you're like, “Oh, my god.”

Ben:  That totally happened to me. Yes.

Casey:  Yes. So, the sticker basically prevents that from ever happening. But, I do think there are several things that you can do to actually improve the likelihood of the sticker staying on for the full 10 days of its Dexcom or two weeks if it's a FreeStyle Libre.

So, some of the key things to remember, always put it on after a shower. When I've really got in the oil off my arm, I think oil on the skin can just totally prevents the adhesive from working properly. So, I'll often use a Dr. Bronner's Castile Soap, which I feel really gets you squeaky clean and really gets oil off and use that. I'll use a little bit of an exfoliator, like a loofah or something on my arm, dry off the skin completely, and then use alcohol. And, sometimes what I'll do, again, to get more oil off, there are alcohol swabs in the kit, but sometimes I'll actually just take a bottle of isopropyl alcohol and put it on a cotton ball and really, really get any oil off the skin. I have found that that makes a really big difference with having the adhesive stay on.

Ben:  Okay.

Casey:  And then, there's other little medical grade stickies like fluids that you can put on your arm that make the skin more tacky before you put the patch on. I don't think those are fully necessary unless you're doing extreme sweaty or sauna stuff. I was just traveling and was doing some sauna every day and my sensor did, unfortunately, I've had a sensor pop off in a sauna. I've had a sensor just fly off in a Bikram yoga class. And so, the heavy, heavy, heavy-duty sweat and heat definitely can loosen that adhesive. So, if I were to do that again, if I knew I was going to be doing hot yoga or going in a sauna, I might use that medical-grade sticky stuff, which you can get on Amazon. And, I'm actually forgetting what the name of that stuff is called, but we could link it in the shownotes.

Ben:  It's like a skin adhesive. I've gotten it before. It's like tacky skin something, but I'll find it and put a link for people who want the extras who are super active or doing, I don't know, a Spartan race with the glucose monitor. And, I'll put it at BenGreenfieldLife.com/glucose.

Okay, I want to talk numbers a little bit. I want to talk numbers. So basically, if you're testing, do you think there's, for the lion share of people, a really good average blood glucose level that you should be looking at during the day? And, this might be a super simple answer, I don't know. And then, on average, how much should it rise after your basic meal and then how soon should it drop back down to normal? I realize that might be a basic question, but I just want to make sure we establish numbers here.

Casey:  I hate to say it, but it's unfortunately not a basic question because the research on this has basically not been done. But, I'll unpack what we do know about numbers.

Ben:  Okay.

Casey:  Unfortunately, it's not like, oh, this is the exact number because you have to remember the way that we have traditionally approached blood glucose values is all through the standpoint of essentially buckets of whether you're non-diabetic, pre-diabetic, or have type 2 diabetes. So, those are the categories that the ADA has put forth. If you're less than 100 milligrams per deciliter, if you're fasting glucose, you're non-diabetic. If you're between 100 and 125, you're pre-diabetic. If you're above 125, you have type 2 diabetes. And so, you're in these buckets, and that's honestly not really helpful for the type of person who's trying to keep optimal levels to make sure that they're preventing chronic disease and hopefully not moving down the trajectory of metabolic dysfunction because you have to remember, I'm sure many of your listeners know this, once you're fasting and blood sugar has gotten up to 100 or reaches the pre-diabetes threshold, there's evidence to suggest that actually metabolic dysfunction has been going on for like a very, very long time. As your glucose has slowly risen throughout the years and probably decades from what would be probably optimal for fasting glucose between about 70 and 80 up to 100. 

And, there's evidence there is a paper in The Lancet that showed that insulin resistance, the process that leads to dysfunctional fasting glucose levels really the root cause of these glucose levels being higher than it should be is starting over a decade before our glucose numbers actually start rising. And, we're really missing that early period of dysfunction mostly because we don't actually check fasting insulin in our standard medical practice, which is a huge problem with the conventional medical system. And, everyone should know what their fasting, I'm sorry, fasting insulin levels. We don't check those. And so, insulin is probably starting to rise many, many, many years before our fasting glucose starts to rise. So, that's a very important biomarker to ask your doctor for. And, we really want our fasting insulin to be below 10, ideally between about 2 and 6. And, that's something we can track before our fasting glucose even starts to go off the rails.

With all that said, your question was more about what is a good average glucose level and what is a good post-meal glucose level. Again, the ADA doesn't tell us this because they're only concerned with whether we're below 100 for our fasting glucose, but there's been several scientific papers that have been published where they basically take in large groups of non-diabetic generally healthy individuals put continuous glucose monitors on them for periods of a few days to a few weeks and just looked at what their glucose actually does. And so, what these studies tell us, if you look at all the research together, is that average 24-hour glucose levels in these healthy populations wearing CGMs are between about 84 and 104 milligrams per deciliter.

Ben:  84 and 104.

Casey:  Yeah. And, I'm summarizing about 6 to 7 papers that basically have all the populations fall between that range of essentially min. 24-hour glucose levels for a healthy population wearing CGM. So, does that mean that that's optimal? Still hard to know, but this is a healthy population. So, that's a good gauge.

And then, I think one other thing to think about with average glucose is that average glucose is, of course, going to factor in what your sort of baseline level is in between meals and overnight, but it also factors in those post-meal elevations. So, if we're talking about like, “Okay, I'm in between meals, I haven't eaten for three hours, I'm not going to be eating for three hours, what do I want my glucose level to be?” It might be even a little bit lower than that average glucose level because that's obviously incorporating the 24-hour pattern. So, I like to stay between about 70 and 90 for my resting glucose in between meals after I've come down from a meal and sort of what I'd like to see overnight.

And actually, there is some research that suggest that might be normal. There's one study that was looking at normal-weight young non-diabetic adults and they looked at pre-meal glucose levels. So, what was their glucose right before they ate, and on average, it was between 72 and 90 milligrams deciliter. So, I think that that's a pretty fair thing to shoot for for pre-meal. 

Then, if you're talking about post-meal glucose levels, which is obviously something that people care a lot about, if again we look at the ADA criteria for what should your glucose levels be after a meal, it's very hard to interpret. They basically say that two hours after a meal, you want to be below 140 milligrams per deciliter. So, you eat, you go up, you come down, and if you're below 140 milligrams per deciliter, two hours after a meal or an oral glucose tolerance test, which is a drink of glucose, then you're categorized as non-diabetic. I personally think that's a ridiculously lenient number. If you're up in the 140s two hours after a meal, that is very, very high. I like to, first of all, not even go up to above 140 after a meal, but go up and then come down within those two hours and be back down to 70 to 90 resting glucose within two hours after a meal. So, I think that's highly lenient and it's not really a great target.

So again, going back to the literature, if you look at those studies of people wearing CGMs healthy non-diabetic individuals, they basically say that peak glucose, so not at two hours but actually, their peak glucose, which generally happens between 45 minutes and an hour after meal is typically on average between 99 and 137 milligrams per deciliter. So, that's like they go up, they peak between 99 and 137 milligrams per deciliter and then they come down within about two hours. 

We have actually surveyed our advisors, our Advisory Board is just an incredible group of thought leaders like Mark Hyman, Dom D'Agostino, Sara Gottfried, Molly Maloof about what their optimal range is after meals are. And, we actually get an even tighter view. So, Dr. Mark Hyman recommends that glucose should not rise above 120 milligrams per deciliter after meals. Dr. Molly Maloof says that most healthy is less than 110 after meals. Dom says less than 120. And, Dr. Sara Gottfried says less than 115 milligrams per deciliter. So, we're all in this sort of 110 to 120 as your peak post-meal glucose.

So, just to summarize all that, I like to stay about between 70 and 90 in between meals, like resting during the day, and not really go above 120 after meals. And, I like to go up and come down within two hours. And, that will pretty much make me feel my best.

Ben:  Okay, got it. That's super helpful.

Now, in people who eat a low-carb diet or people who are keto, I think this flies under the radar, and I'd love to hear your take on this. There's this phenomenon, and I guess what it's called is adaptive glucose sparing, meaning if you eat a low-carb diet, you actually develop this insulin resistance because essentially your muscles prefer to use fat as a fuel. So, the action of insulin brings sugar into the cells for energy because they don't necessarily need as much sugar. Thus, the sugar in the bloodstream stays elevated. 

So paradoxically, somebody could be eating it like a low-carb ketogenic diet and their average might be 90 to 100, whereas that same person, if they weren't eating a low-carb or keto diet, they might be more 80 to 90 simply because the muscles are using the fat, so the sugar stays a little bit higher in the bloodstream. And then, furthermore, it might not be as much of an issue for chronic disease if that is the case because that person who's following the low carb or ketogenic diet is so insulin sensitive that the high blood glucose is not necessarily associated with insulin resistance or very high levels of insulin or too much stress in the pancreas. Have you come across that phenomenon at all? Was there anything to it?

Casey:  Yeah. This is the fascinating, fascinating topic, this paradoxical rise in blood glucose on a low-carb diet. And, I'd say the person who's really the expert on this is one of our advisors, Dr. Ben Bikman. And, he actually has a name for this, which is called Reverse Metabolic Inflexibility.

Ben:  Reverse metabolic inflexibility.

Casey:  Yeah.

Ben:  Okay.

Casey:  And, we can link to a blog post on this that he's written for the Levels blog, but it's really fascinating and it's mostly what you would see in a long-term keto diet and not in everyone. I think it's in part due to what you're saying is that the average American is stuck in a glucose-burning mode. And, when you shift the body to being almost exclusively in a fat-burning mode as a result of low insulin levels, which is a healthy state, your body is less responsive to insulin because it's not using it much. And so, it may take longer for a glucose load with a meal to clear. And, this may also have to do with the hormone glucagon. So, glucagon is a hormone that antagonizes the actions of insulin. So, insulin is a glucose-lowering hormone and glucagon is a glucose-raising hormone through gluconeogenesis in the liver and then glycogenolysis. So, breaking down glycogen into glucose and then making glucose from other substrates in the liver.

And basically, if you are on a long-term low-carbohydrate diet, you may end up driving up glucagon levels because your body is essentially being stimulated to make glucose because you're not consuming glucose. And also, dietary protein stimulates glucagon. And, since a low carb diet is going to have probably higher ratio of protein, you may be stimulating more glucagon. So, there may be an element of the body actually just responding to the fact that you're consuming low exogenous carbohydrates by stimulating hormone that's going to bring glucose back up a little bit. And, that's of course in the context of super low insulin levels because you're on a super low-carb diet. So then, the question is in the context of low insulin levels, is this slightly higher glucose a problem?

Ben:  Yeah.

Casey:  The answer to that is not known. However, I will say that Ben Bikman, I don't want to speak for him, but I think feels that the physiology is very different than normal hyperglycemia and it's probably not something that people should worry too much about if their glucose is just slightly bumped up 10 milligrams per deciliter for instance on average in the context of very, very low insulin levels.

Ben:  Yeah. For sure tend to trend a little bit high if I'm being super strict on carbohydrates. But again, I think it's a non-issue. Obviously, glucose levels aren't necessarily caused by face feeding with sugar and high starches all the time. So, I personally don't think it's as much of an issue and would probably tend to agree with Ben Bikman on his whole take on that. So, maybe I'll include a link to a helpful article about that and an explanation of it in the shownotes at BenGreenfieldLife.com/Glucose.

Alright, let's talk about some fun stuff. Obviously built into the Levels app is the ability for people to run experiments like what happens if I eat oatmeal versus eggs for breakfast or cold shower versus hot tub like all sorts of things. So, obviously, you guys have collected some data. What I'm curious about is most people know, “Oh, if you walk after a meal, your blood sugar is going to be low.” Or, “If you lift weights, maybe before a meal, your blood sugar is going to be low.” But, is there anything that's popped up that's been super interesting as far as surprising or unexpected results from people experimenting with what might cause their blood sugar to be low or high. And, if so, what are some of the more interesting takeaways that you found?

Casey:  Oh, my gosh. People are doing so many fascinating experience and might be one of the most fun parts of this job is to see what people are posting on social media, tagging Levels of what they're trying, Wim Hof breathing and cold plunging, and all sorts of stuff. I'll mention a few of the ones that are my favorite. 

I will say some of the really basic experiments are some of the ones that are most life-changing. You mentioned walking after meals. That's one that we've actually studied in our community at a bigger scale and it's pretty profound. I'll just mention briefly, we did this study where we sent people 12-ounce cans of Coke. So, they basically drank a Coke one morning, and then the next morning under hopefully very similar conditions, similar sleep, similar stress levels, et cetera. They drink a Coke and then walked after the coke just like a gentle walk. And, we actually found that the median glucose rise between a walk and no walk was actually 33%. So, the peak went from 162 milligrams deciliter to an average of 132 milligrams deciliter. So, that's a huge difference. You can imagine over the course of your lifetime if you're always 30% lower on your glucose spikes, that's pretty monumental. So, that was really cool to see.

We just had a member post an amazing reel that she did with Levels basically showing. She tried two different breakfasts that were isocaloric. So, exact same calories and one breakfast was eggs, sauteed brussels sprouts in onion, half an avocado, and blueberries. And, the next was two pieces of whole grain gluten-free toast, one tablespoon of peanut butter, and 3/4 cup of OJ. So, a very like what some people would say is like, “Oh, that sounds like a sort of healthy breakfast.” The eggs, avocado, blueberries, Brussels sprouts, she had a 20 milligram per deciliter rise and was above target for only 45 minutes. And, with the bread, peanut butter, and just a small cup of OJ, she went up 79 points and was above target for 98 minutes. And so, it just goes to show that if you looked at both those breakfasts, there's a lot of people who would say that that seems a reasonable — whole grain toast, peanut butter, a little bit of OJ, but it absolutely threw her glucose through the roof.

Ben:  Yeah.

Casey:  So, just having obviously a more whole foods-based protein and fat-rich, healthy protein and fat-rich breakfast.

Ben:  She probably could add scrambled eggs and glass of orange juice and the orange juice still would have done that. I mean, any fruit-based sugar apps and a fiber, even some fruits like grapes and raisins, those massively spike blood glucose like sometimes higher than just like pure sugar. It's crazy because they're just a very sweet fruit without a lot of fiber to slow down that release of blood glucose. Yeah, even grapes can be an issue, or a glass of wine. It is kind of interesting.

Now, what about dairy? Because dairy is very insulinogenic. It's one of those things that seems to be associated in many people with weight gain. Does dairy seem to spike blood glucose in a lot of people?

Casey:  It's funny. It actually doesn't and it depends on the dairy source. But, for instance, a lot of people end up posting on Twitter that they eat ice cream and they don't have a glucose spike and they're so excited. And, I think, unfortunately, this is one where it's very, very nuanced because, in a sense, ice cream is this balanced meal. It's got protein, fat, and no fiber obviously, but it's got carbohydrates, protein, and fat. And so, it's likely that that protein and fat are offsetting the high sugar. That doesn't necessarily mean it's healthy to eat that sugar, but the thing about dairy, like you said, it's highly insulinogenic. And so, the dairy proteins are known to potentially spike glucose six times higher than other protein sources. And so, that does actually cause me a little bit of concern about eating too much dairy because obviously, we don't want our insulin to be high. And so, it's something that you may see glucose not rising with a dairy-based product, but it might be at the expense of very high insulin levels after that meal.

Ben:  Okay. What if somebody does a dairy substitute like rice milk, or oat milk, or almond milk, or something like that?

Casey:  Oh, my gosh. We actually did an amazing community experiment with oatmeal. And unfortunately, the results were not favorable for oat milk. But basically, we'd heard reports from members that oat milk was causing really big spikes for them. So, we did an experiment with it. We basically had people either have their coffee with oat milk or have their coffee with unsweetened nut milk of any other kind. So, macadamia, almond milk, cashew milk —

Ben:  And, the oat milk was unsweetened, too.

Casey:  Well, most oat milk technically says unsweetened, but I think it can be a little bit tricky because the way the oats are processed, even if they're not adding refined sugar, the way they're processing the oats does lead to a lot of highly accessible essentially refined sugar. It may not be added but the way the oats are processed can essentially make it very glucose-spiking. 

And, what we saw in this study was that for people who had their coffee with oat milk, they had an average glucose spike of 29 milligrams deciliter. And, if they used any other type of unsweetened nut milk, it was 9 milligrams per deciliter. And, the people who uses the oat milk their average, above range. And, our top of our range is 110 milligrams per deciliter. They were above range for 42 minutes. And, if you used any other type of unsweetened nut milk, it was 11 minutes above range.

And so, that was one of our experiments that really I think had the biggest difference. And, this was again to just test some anecdotal reports that we've gotten amongst our team and amongst our members. And then, studying it in a larger group of people, we did see that. So, I definitely avoid oat milk knowing what I know now from our data set.

Ben:  Okay.

Casey:  And, another interesting one we did was on resistant starches. So, essentially this concept of if you take a starchy food like a potato or rice and you eat it fresh out of the stove or oven versus if you take that food and then you cool it and eat it cooled or reheat it, the idea is that some of the carbohydrates in the cooling process actually transform into a form that's indigestible, a resistant starch. And so, we had people do this with rice and it was actually quite interesting as well. The people who just ate fresh hot rice had an average glucose response about 38 milligrams deciliter and if they cooled it, it was 26 milligrams per deciliter. So, it was fairly significant. And, of course, these are not super controlled scientific studies, but we love to do group experiments with our members.

And, one other that you might be really interested in just being an athlete, we're doing a study right now with our members or sort of a group community experiment where people are essentially trying to figure out their exercise threshold that does not spike their glucose. So, you may have noticed on your CGM that with high-intensity interval training or powerlifting or things that are sort of above all-out efforts or generally above VO2 max of about 80%.

Ben:  Yeah. Well, to interrupt you quickly, anything stressful, sauna session, anything that your body gets the message that it needs to run from a lion, you get that transient rise in blood glucose that I've said many times before in a podcast isn't something to be that concerned about because that results in long-term insulin sensitivity and long-term lower blood glucose. It's kind of like your heart rate. When you exercise, your heart rate goes up, but the long-term effect of that is a lower heart rate.

Casey:  That's exactly right. And, that's the key point. When you do these high-intensity exercises or any, but when you do the high-intensity exercise, you're often going to see your glucose spiking. And, that's the body feeling like, “Okay, I'm running really hard, this must be some sort of threat. I need to mobilize glucose to feed the muscles.” The liver actually dumps out glucose for the muscles to use. And, you often see a glucose spike with high-intensity exercise.

And, with lower intensity exercise like zone two, walking, light jogging will often see a decrease in glucose because you're just utilizing, you're not putting your body into a stress response, you're not mobilizing that glucose from the liver and you're just using circulating glucose and so it's going to dip a little bit. So, we're having members essentially see at what point do they flip from that more picking up circulating glucose and it dropping. So, a low-intensity exercise, which is we'd associate more with the fat-burning state as well because the body is going to be more favoring fat oxidation and that lower intensity exercise versus when do you flip into high-intensity glucose rising. So, for each member, it's going to be a different strenuousness level.

Ben:  Yeah.

Casey:  And so, that's something that we're trying to study and figure out whether we can kind of figure out what is sort of the flip from fat burning threshold to more glucose utilization threshold for an individual member.

Ben:  Yeah. What about gum?

Casey:  In what sense? 

Ben:  Let's say you're chewing gum, let's even say it's not a gum that has sugar in it, which might cause blood sugar to go up a little bit, I guess. But, has anybody done any tests on gum? Because I chew a lot of gum.

Casey:  I have not seen any experiments on that. Have you noticed anything with your CGM with gum?

Ben:  Not really. I mean, it obviously causes a little bit of a rise in incretin hormones because the taste of something in your mouth and your body prepares to digest food. So, it's possible that in a similar way that having bitters before a meal or apple cider vinegar, cinnamon might lower blood glucose. If they're technically is a hormonal response that results in the body's ability to be able to process fuel or calories a little bit more effectively, you could expect it to lower blood glucose. But then, again, if the gum is caffeinated or has nicotine, et cetera, and sympathetically stimulating, they raise blood glucose. Yeah, tough to say. I don't have any data. I'm just curious.

Casey:  I got to try it now.

Ben:  I know. I might have too as soon as I get my freaking sensor to start working. Okay, so that covers a few of the surprising things.

Now, what about the things that most people probably don't know about? We talked about exercise. We talked about cold. I mentioned some of these blood glucose disposal agents like Ceylon, cinnamon, apple cider vinegar, bitter melon extract, we know a lot of those can lower blood glucose. Anything surprising that controls blood sugar that you think more people should know about?

Casey:  Yeah. So, you hit a lot of them. I think some of the surprising things that will raise glucose is, like you said, high-intensity exercise, stress, and heat. Of those three, I don't worry too much about heat or exercise because as you said, the long-term, those are going to actually improve insulin sensitivity. However, with stress raising blood sugar, I do think that's probably maladaptive.

Ben:  Yeah, but that's not that surprising for people. I think everybody knows stress is going to raise it. What about the microbiome? I was hoping you might mention something about that because obviously now people are selling probiotics that they say will lower blood glucose. I have some in my pantry. I haven't tested them yet, but apparently, if you have levels of a certain bacteria in your gut, you're better able to manage carbohydrates. And furthermore, and this is super interesting, I did a podcast about this a while ago that if you're accustomed to eating a high carbohydrate diet, you tend to build up a bacterial profile in the gut that results in your body actually experiencing low blood glucose and energy destabilization unless you feed it carbohydrates, which might factor into this whole idea that a lot of people will have to be on a low carb diet for 8 to 12 months before they really notice that shift in the gut biome and the shift in the ability to feel good and have adequate energy levels. So, what's the link between the gut and the blood sugar?

Casey:  Yeah, I mean, massive link between gut and blood sugar. Really more and more research literally every day is coming out showing that what's happening in our gut has a direct impact on our mitochondrial function and our insulin sensitivity and glucose homeostasis. I think on the probiotic front, the strain that is coming out with the most compelling research I think for improving metabolic health as a supplement is Akkermansia that might be the one that you have. But Akkermansia, there's hundreds and hundreds of papers about it basically showing that it has impact on metabolism in general health. And, it's been shown in mice to basically improve metabolic disease and improve glucose homeostasis. And, the mechanisms for it are thought to be a few things. One is increased thermogenesis, so it actually induces uncoupling proteins in brown fat and essentially just make you hotter, make your basal metabolic rate higher.

Ben:  Yeah.

Casey:  It also helps secrete GLP-1, so one of our gut hormones intimately involved in metabolic health, it's a bacteria that lives in the mucin layer of the gut. And, we know this mucin layer is so important for gut integrity. And, with the diets we're eating today, we're depleting our mucin layer. And so, it's a mucinophilic gut microbe that really protects that mucin layer. And, it's been shown to help with maintenance of tight junctions between our colon cells and produces antimicrobial peptides in the gut and really restores mucin thickness. And so, all of that is, of course, so important for the concept of gut integrity and leaky gut and general inflammation in the body that's related to gut dysfunction. And so, that's a really promising one that's now being commercialized. There's a company Pendulum Therapeutics that's selling Akkermansia.

Ben:  Yeah, I heard about Pendulum. Yeah. Somebody mentioned that Dr. William Davies, when I interviewed him, we talked a lot about yogurt and specific strains of yogurt like L. reuteri stabilize blood glucose, and he mentioned the Pendulum company as one that's relevant. I haven't started taking it for two reasons. One, I just haven't got my hands on it even though I do have a bottle from a different company up in my pantry. I forget the name of it. There's a few now that are making it. 

And then, two, full disclosure, like I developed a blood glucose stabilizing supplement that works pretty well for me that Kion sells with the bitter melon extract and chromium and vanadium and astragalus and a few other decently researched blood glucose stabilizing agent. So, I kind of just go with that because I know a guy and I get a good deal on it. So, there are other things like dihydroberberine is one that my friend Shawn Wells swears by is a form of berberine that works really well. 

And then, I've mentioned this so many times, I won't dwell on this, but I have found nothing, nothing to control blood glucose more effectively than a bout of morning cold thermogenesis. And, that is why every day, even throughout the winter, cold shower, cold soak, cold by the water, something cold, even a brisk cold walk with wearing limited clothing. I'm not walking around the neighborhood in my G-string, but shorts on and sandals in the winter. Oh, my gosh, your blood glucose. I've been in the 40s to 50s until like 3:00 or 4:00 p.m. if I do a morning cold swim or something like that. It's crazy.

Casey:  It is wild. And, you mentioned your supplement. I think that those like chromium and others. We talk a lot about something like the more esoteric things that we could use for metabolic health like berberine and things like that like cinnamon, but I think one key thing that I think about a lot is just our basic micronutrients. We actually need those to be in a good place in our body for our electron transport chain, our mitochondria to work properly, like a lot of these enzymes that are super related to glucose processing and energy ATP production in the body like in the mitochondria are dependent on micronutrient cofactors which many Americans are actually depleted in because of our poor standard American diet.

So, aside from some of the fancier stuff like Akkermansia, and I take some other mitochondrial support supplements like Urolithin A, but even just basic stuff like vitamin D, magnesium, selenium, zinc, B vitamins, manganese, vitamin C, omega-3s, chromium, these things are critical just for baseline cellular metabolic functioning. And so, just making sure people are knowing what micronutrients are key to these processes and then making sure they're getting them in their diet. And, if they can't, supplementing with them, so I certainly supplement with magnesium and vitamin D and omega-3s and things like that because I think especially with what's going on with our conventional farming and our poor soil health in the country, so much of our food is actually more micronutrient deplete than it was 50 or 100 years ago. 

So, even if you're kind of eating a perfect whole-food diet, you still might be getting fewer of these key micronutrients or metabolic health than you would if you were eating food that was grown on better soil. And, that goes for both plants but also for meat, meat grown, meat that has eaten plants that were grown on good soil have much higher levels of omega-3s and micronutrients and even phytonutrients, which we often think of being only in plants. But actually, animals can be a source of phytonutrients, but really only if they're raised on plants that were grown in good soil. So, just the basics, I think, are also a big part of the conversation too as much as I also do try some of these other more advanced things like Mitopure with Urolithin A or Akkermansia or berberine or things like this.

And then, one last thing I think I would mention is just uric acid is another big piece of this whole metabolic puzzle. We know that fructose and high fructose corn syrup raise uric acid levels which creates mitochondrial oxidative stress and can really create problems with insulin resistance. And, Rich Johnson and David Perlmutter both wrote books this year on uric acid, “Nature Wants Us To Be Fat” and “Drop Acid.” And, there are several supplements that actually specifically improve your acid levels, which are of quercetin, luteolin.

Ben:  Tart cherry, quercetin, I know two.

Casey:  Yeah, quercetin, tart cherry, luteolin, DHA, vitamin C, and chlorella are the big ones. And so, there's just a lot of different tools in the toolbox. And frankly, I take a lot of them and I find benefit from a lot of it. But, I think food is medicine, and getting the basics of those key micronutrients through food that's grown in good organic or regenerative soil is pretty foundational for just the basic cellular physiology.

Ben:  Yeah.

Last question, do you think that there's a possibility in the future based on what's in the interstitial fluid you could like slap a CGM on and it could also be measuring, I don't know, cortisol or inflammatory markers or lactic acid or something like that? Or, is that just not even something on the radar?

Casey:  It's definitely on the radar. And, the exciting thing is that Abbott is actually coming out with three new sensors, which is lactate, alcohol, and ketones.

Ben:  Oh, wow.

Casey:  They're all going to be on separate sensors. So, the dream would be that they're all in one sensor, but we're not there yet. But, I think this is massive progress for the field because I mean, I am so excited to have a ketone monitor on one arm, a CGM on the other arm, a lactate monitor on my butt. Just like —

Ben:  Yeah. It'd be nice if one sensor could it all though.

Casey:  I know. I know. But, the Abbott Lingo is the new series that's coming out. My absolute dream would be continuous cytokine monitors, something that measures oxidative stress, ketones, glucose, some sort of byproduct of the microbiome like short-chain fatty acids, just something that can really tell you about what is the actual like how is your actual physiology doing under the hood. But, we really are believers that this whole concept of continuous biosensors and really having a movie of what's going on inside your body is the future of healthcare and of patient-empowered healthcare especially because if you understand more about your body and how your choices are impacting your health in real-time, which we call biologic observability, you can't control a system that you can't observe. And, the more we're being able to observe our own bodies inside, the better it's going to be, I think, for reversing our chronic disease epidemics. So, there's definitely strides being made with these new sensors. And, I think we're going to see vastly more over the next 10 years. And, Levels's goal is really to help create the software layer that integrates a lot of these data streams to empower individual human health.

[01:16:48] Closing the Podcast

Ben:  It's pretty sweet. And, I dig the app. I'll put our link to it and everything in the shownotes. So, if people want to sign up and use it. And, it's super fun, it's super fun to test this stuff. I had all sorts of questions about this. You asked them. I can keep going, but we're out of time and maybe we'll have to do a round two. But, in the meantime, I'm going to link to as many resources as possible. If people go to BenGreenforLife.com/glucose, I'll put our special link to Levels. I don't know what we have for a link or a code or whatever, but I have something where you save money or get moved to front line or whatever benefits —

Casey:  Levels.link/Ben.

Ben:  There we go, levels.link/Ben. And so, check all that out and you too can join the club of strange freaks who look like robots walking around as modern-day cyborgs tracking our blood glucose 24/7. You can be part of that cool club too. So, BenGreenfieldLife.com/glucose.

Casey, thanks so much for coming on and sharing all this stuff with us. I don't know who else would have been able to answer all my questions other than you. So, thank you.

Casey:  Oh, it's an honor. I love your content. I so appreciate what you're doing for the world and I'm so grateful. Good to have this convo.

Ben:  Awesome. Alright, folks. Well, I'm Ben Greenfield along with Casey Means signing out from BenGreenfieldLife.com. Have an amazing week.

More than ever these days, people like you and me need a fresh entertaining, well-informed, and often outside-the-box approach to discovering the health, and happiness, and hope that we all crave. So, I hope I've been able to do that for you on this episode today. And, if you liked it or if you love what I'm up to, then please leave me a review on your preferred podcast listening channel wherever that might be, and just find the Ben Greenfield Life episode. Say something nice. Thanks so much. It means a lot.



If I asked you to make a list of foods that you predict would spike your blood sugar, what would be on your list? Coca-Cola? Twinkies? Frappuccinos?

Probably not steak and green beans, right?

Well, as it turns out, steak and green beans spike my blood sugar. I wouldn't have predicted that, either, before I started wearing a continuous glucose monitor (CGM). You've likely heard of CGMs, because they're a big trend in the health industry right now.

Now, if you haven't heard of CGMs, what they do is pretty self-explanatory. They monitor your glucose…continuously.

Paying attention to your blood sugar is one of the most important things you can do for your health. Poor glucose control is most often associated with diabetes, but it also affects a range of chronic conditions, including Alzheimer's, stroke, heart disease, and more. It can also lower your day-to-day energy levels, impede your ability to control your weight, and decrease your sexual function.

I wear a CGM from a company called Levels. As a self-proclaimed tech geek, I appreciate that the Levels app goes way beyond most companion apps for CGMs. Until I was a Levels member, I thought I understood my metabolic health pretty well. I definitely didn't expect steak and green beans to be on the watch list. But because your body's glucose response to food is highly individual, there's no way to know until you test.

It's not just me. Everybody seems to be slapping a patch on their arm to track their blood sugar, even if they're not diabetic. And for good reason. The host of benefits derived from such a monitor are many. But there are a ton of subtle nuances and questions I personally have about these things, such as:

-From a cellular standpoint, what is it about a rise in blood sugar that remains high in the bloodstream for extended periods of time, or high amounts of glycemic variability, that actually seem to be causing the primary issues with predisposition to chronic disease?

-What would be some of the reasons that healthy, fit people might still have high glycemic variability?

-From a numbers standpoint, what is a good average blood glucose level, how much should it rise after a meal, and how long should it take for it to return to baseline?

-What sort of things besides starch/sugar/carbohydrates are the most significant things to consider when it comes to things that people might not know would raise their blood sugar levels?

-From a supplementation, lifestyle or biohacking standpoint, what are some of the more powerful ways to control blood sugar that most people don’t know about?

-When is blood sugar going “too high” not an issue?

-What are the primary differences in accuracy and the way that blood sugar is measured between a typical blood stick, a blood lab measurement from a test tube, and a continuous blood glucose monitor?

-When is it necessary to recalibrate a CGM?

-Tips for placement of a CGM on the body, and how to ensure that it sticks for as long period of time as possible?

-Are there any concerns about EMF exposure when using a CGM?

-Is there any capability for a CGM to eventually continuously monitor other things, such as cortisol, cholesterol, inflammatory markers, etc.?

-If you don’t have diabetes, will insurance cover this, and if not, what is the approximate cost?
And much, much more…

Casey Means, MD, my guest on today's show, is the Chief Medical Officer and Co-Founder Levels, Associate Editor of the International Journal of Disease Reversal and Prevention, and she guest lectures at Stanford University.

Casey's mission is to maximize human potential and reverse the epidemic of preventable chronic disease by empowering individuals with tools that can facilitate a deep understanding of our bodies and inform personalized and sustainable dietary and lifestyle choices. Dr. Means’s perspective has been recently featured in the New York Times, Wall Street Journal, Men's Health, Forbes, Business Insider, Techcrunch, Entrepreneur Magazine, Metabolism, Endocrine Today, and more.

There are a ton of subtle nuances and questions I personally have about CGMs. Since I've never done a full podcast on the nitty-gritty of these things, like where to put them, how they work, the differences between brands, and more, I asked Casey to tell me everything she knows about blood sugar and CGMs.

During our discussion, you'll discover:

-Where to wear the CGM for accuracy so it doesn't hinder daily activities…08:53

  • Casey likes to wear it on the back of her arm; basically the standard place 
  • 3 companies making these sensors:
  • Levels performance cover – covers the sensor that makes it essentially waterproof and sweatproof

-How exactly does the CGM gather sugar data?…11:53

  • Hair-like filament goes into the skin – needle immediately retracts
  • A part of the filament is sticking in the plastic sensor that's affixed to the outside of your skin
  • The part of the filament that is inside the skin is sitting in the interstitial fluid
  • The filament is coated with an enzyme called glucose oxidase that initiates a chemical reaction, like an actual lab test in your arm,  every 15 minutes and sends that test information to your smartphone

-Differences in accuracy and measurement between a typical finger prick using blood and a continuous blood glucose monitor? When is it necessary to recalibrate a CGM?…14:34

  • Before the widespread use of CGMs, blood sugar was measured by pricking the finger 
  • CGM levels, use interstitial fluid, may be 15 minutes delayed from a blood reading 
  • All sensors are factory calibrated, so it does not require calibration
  • Dexcom G6 has the functionality to allow adjusting readings by putting blood from a finger prick to the G6 app
  • 9% difference from blood on average and FDA approved as a standard for wearables

-Are there any preferred brands or any brand considered to be a gold standard?…18:41

  • There is no reputation of one brand being a gold standard, but the market share major players are the FreeStyle Libre and the Dexcom G6
  • FreeStyle Libre uses near-field communication, which means that you take your phone and hold it up to the sensor to scan it to transfer the data from the sensor to the phone
  • Dexcom G6 uses Bluetooth and streams data straight to your phone
  • It's kind of anecdotal but feedback from users is that the FreeStyle Libre tends to run low while the Dexcom tends to run high
  • Casey's experience comparing finger prick results to sensors results: 85 mg/dL for a finger prick
  • The main purpose of these sensors is to understand trends throughout the day and the difference between pre-meal and post-meal readings

-Are there any concerns about dirty electricity or EMF exposure when using a CGM?…22:07

  • YouTube videos reviewing CGM EMF levels
  • EMF emissions of the sensors are understudied in a formal way
  • Casey shares what her acupuncturist told about how CGM impacts energy flow in her arms

-What kind of things might cause the sensors to fail or give an inaccurate reading (e.g., could things like heat, cold, etc. cause inaccurate sensor readings)?…24:58

  • Operating temperature of these devices is from 50°F to 113°F
  • Sauna or a cold plunge puts the device outside its range of operating temperature, probably causing sensor issues
  • A bit of blood coating the filament sometimes makes the sensor fail (Casey's personal experience)
  • Sensors failing after an extended fast – probably has some sort of algorithm built in that basically says, if it's reading values that are essentially incompatible with life, it's probably broken, and it just stops itself 

-Do infrared lights, PEMF, or vibration platforms cause sensors to fail?…31:42

  • Casey has not encountered any failures caused by the gear mentioned
  • Looking forward to discovering more answers to Ben’s questions as the volume of usage goes higher
  • There has been feedback about substances interfering with the sensors
  • Medicines and supplements that interfere with the chemical reaction on the sensor (dose-dependent)
    • Vitamin C – interferes with glucose oxidase
    • Salicylic acid (aspirin)
    • Hydroxyurea (cancer treatment drug)
    • Tylenol used to have issues 
  • Dehydration can lead to false readings

-If you don’t have diabetes, you can still get the sensor and the app, but does insurance cover it? If not, what is the approximate cost?…35:01

  • Levels is now exclusively a wellness product and is not intended for disease management or disease prevention
  • Levels is meant for people who are trying to live their healthiest lives, trying to understand their bodies better
  • Helps people understand how food affects their health
  • Traditionally, CGMs were used exclusively as a medical device in a clinical setting Levels brought this device to a mainstream consumer audience of people who are optimizers are interested in general health and wellness

-Any tips for placement of a CGM on the body and how to ensure that it sticks for as long as possible?…42:27

  • Levels performance covers are intended to go over the sensor to make them more waterproof, more sweatproof, prevents the sensors from getting dislodged 
  • Stick it on after showering; oils on the skin prevents it from sticking for the full 10-14 days
  • Casey recommends Dr. Bronner's Castile Soap
  • Apply alcohol on cotton, rub on the skin surface to remove excess oil before sticking it 
  • Skin adhesive

-What is a good average blood glucose level? How much should it rise after a meal, and how long should it take for blood glucose to return to baseline?…43:36

  • There is no research available at the moment
  • ADA (American Diabetes Association) categories:
    • If your fasting glucose is less than 100 mg/dL, you're non-diabetic
    • If you're between 100 and 125 mg/dL, you're pre-diabetic
    • If you're above 125 mg/dL, you have type-2 diabetes
    • If your blood sugar has gotten up to 100, the pre-diabetes threshold, metabolic dysfunction has been going on for a long time 
  • Insulin resistance underlying type 2 diabetes – The Lancet article
  • Importance of knowing your fasting insulin levels
    • Should be below 10, ideally between 2 and 6
  • 24-hour glucose levels in non-diabetic, healthy populations where CGM is between about 84 and 104 
  • Average glucose is a factor in what your baseline level is in between meals and overnight, but it also factors in post-meal elevations
  • What should your glucose levels be? Here’s the ultimate guide to healthy blood sugar ranges – Levels Health article
    • Normal weight, young, non-diabetic adults pre-meal glucose levels: on average, between 72 and 90 mg/dL
    • Post-meal glucose levels below 140 mg/dL 
  • Surveyed Levels advisors Mark Hyman, Dom D'Agostino, Sara Gottfried, Molly Maloof, about their optimal ranges after meals:
    • Dr. Mark Hyman – glucose levels should not rise above 120 mg/dL after meals
    • Dr. Molly Maloof – most healthy is less than 110 mg/dL after meals
    • Dom D'Agostino – less than 120 mg/dL after meals
    • Dr. Sara Gottfried – less than 115 mg/dL after meals
    • Dr. Casey Means – between 70 and 90 mg/dL in between meals, not exceed 120 mg/dL after meals and go up and come down within 2 hours

-Adaptive glucose sparing…51:19

-What are the most interesting experiments people have been running on levels with their blood sugar, and what have been some of the more surprising or unexpected results from those experiments?…56:08

  • Study: Taking a walk after drinking a Coke in the morning
    • Median glucose rise between a walk and no walk was 33%
    • Peak went from 162 mg/dL to an average of 132 mg/dL
  • Another feedback: two different breakfasts, same calories
    • Healthy one – had a 20 mg/dL rise and was above target for only 45 minutes
    • Bread, 1 tablespoon of peanut butter, and 3/4 cup of OJ – went up 79 mg/dL and was above target for 98 minutes

-Does dairy spike blood glucose?…59:11

  • It depends on the dairy source
  • Dairy proteins are known to spike glucose 6x higher than other protein sources

-What about other dairy substitutes like rice milk, oat milk, and almond milk?…1:00:24

  • Did community research for oat milk – feedback was that oat milk was causing big spikes
  • Coffee with oat milk had an average glucose spike of 29 mg/dL
  • Coffee with other non-sweetened nut milk had an average glucose rise of 9 mg/dL
  • People using oat milk had an average time above range (above 110 mg/dL) for 42 minutes
  • People using any other type of nut milk had an average time above range of 11 minutes
  • On resistant starches – What is resistant starch, and how does it impact glucose? – Levels article
  • Another community research they are doing is how to figure out people's exercise threshold that does not spike glucose

From a supplementation, lifestyle, or biohacking standpoint, what are some lesser-known ways to control blood glucose?…1:06:27

-In the future, based on what is in the interstitial fluid, could a CGM eventually measure cortisol, inflammatory markers, etc.?…1:14:47

  • Abbott is coming out with 3 new sensors to measure lactate, alcohol, and ketones
  • These are going to be different sensors
  • Abbott Lingo
  • Biosensors tell you how your actual physiology is doing
  • You cannot control a system that you cannot observe
  • Levels goal is to help create a software layer that integrates these data streams
  • levels.link/ben

-And much more…

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Resources from this episode:

Casey Means, MD:

– CGM:

– Podcasts:

– Books:

– Other Resources:

Do you have questions, thoughts or feedback for Dr. Casey Means or me? Leave your comments below and one of us will reply!

Episode Sponsors:

Levels: If you want to better understand how food affects your health and try a continuous glucose monitor, go to levels.link/Ben to learn more. They also have a well-researched, in-depth blog that I recommend checking out if you want to learn more about metabolic health, longevity, and nutrition.

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