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.

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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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Click here for the full written transcript of this podcast episode.

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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6 thoughts on “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.

  1. Justin says:

    I feel like I’m missing something here… This podcast sounded like it was going to be about Levels but all you two talk about is the Dexcom and the freestyle libre. Aren’t Levels, dexcom, and libre all different products? or does levels use dexcom and libre sensors? I’m so confused.

    1. Levels is the app (software). Dexcom and / or Freestyle are the sensors (hardware). :)

  2. Ben Dobson says:

    Can you do a podcast on BJJ and what you would do to best be prepared for BJJ at semi competitive/ hobby level.

  3. Vinnie says:

    I keep two Gel Cold Sleeve Wraps in my freezer and bring them in the sauna with me to put over my Libre CGM to keep the temp in the operating range.

  4. Eleanore says:

    I have worn a dexcom g6 for 3+ years and have sat in a clear light sauna every night for the same amount of time. I have never had a transmitter fail that way. the only time a transmitter failed on me was when I had it on using my multi wave oscillator. I believe the human charger device you have is similar to a MWO and could be disrupting your transmitter and making it fail. If I want to use my MWO while I’m in a middle of a 10 day sensor, there is a way to take out the transmitter without disrupting the sensor. so you can do a treatment in the human charger, then put the transmitter back in. there are a million video on YouTube about how to take out a transmitter (mostly for the purpose of using a sensor for more than 10 days–which is totally possible).

  5. Kelly Candeur says:

    How come my blood glucose takes a deep dive with cold plunge. I see most people have a temporary spike.
    Thank you!

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