Glucose higher in endurance athletes?

I will follow up tomorrow, but suffice it to say that the comparison groups were healthy individuals.

ETA promised follow-up:

Controls in this study were sedentary blood donors from northern Italy, none of whom had elevated HbA1C and in the opinion of the investigators were consuming a typical Mediterranean diet. No information is provided in the paper re. matching for age, body mass, etc., but note that there was even a difference in fasting plasma glucose between the pro cyclists and the elite cyclists (i.e., conclusion isn’t based only on comparison w/ controls).

This study also observed lower fasting plasma glucose in higher level vs. lower level athletes. The former group consisted of “international- and national-level swimmers were from the Shanghai and Zhejiang professional swimming teams as the elite group. Athletes in the elite group have participated in international or national swimming competitions.” The latter group was composed of “first- and second-grade swimmers were from the Shanghai professional swimming team, Shanghai University of Sport, Shanghai Jiao Tong University, and Tong Ji University as the sub-elite group. Athletes in the sub-elite group have participated in provisional or universities swimming competitions.” The two groups were well-matched for age, body mass, and years of training.

I’m still looking for the other article(s) I had found.

TL,DR: The conclusion that athletes have lower fasting plasma glucose is not dependent upon comparison with individuals with impaired glucose metabolism.

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just going to leave this link here for a video I watched in case someone in the future stumbles upon this thread and it helps them. more about psychological aspects of CGM. it’s at a third grade comprehension level - perfect for me :slight_smile:

more of what you all (and the Inside Exercise link Dr. Andy posted) have been saying about being careful with these things.

I am happy I got it because it will be the impetus for learning more about nutrition and myself - and ultimately changes in habits / behavior. but I wish I read this thread and came into it with a different mindset.

Speak of the devil:

(Still digesting - ha! - this, but my first takeaway is just that interstitial glucose concentrations are highly variable…about as bad as blood pressure, really.)


I doubt it’s been specifically studied, but I haven’t looked at the literature on this.

Paging dentists or tooth scientists! (is that a thing?? If so, I want to talk to you.)

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Could you point me to the time stamp in the video for this?

From the study:
“Future research is needed to determine if an ideal glycemic range exists for endurance competition and/or performance in healthy athletes and if CGM can be used to target this range by further optimizing any already existing evidence-based nutritional intake strategies for performance.”

THAT’S the research I want to see….

Reading this thread is like watching an exercise phys./clinical medicine Avengers movie. Teaming up to take on low-carb Thanos.


I think that the ideal range is already known: the higher, the better.

I say that because although carbohydrate ingestion during exercise doesn’t reduce the utilization of muscle glycogen, infusion of glucose high rates to roughly double plasma concentrations does (albeit only slightly).

Of course, you can’t readily achieve such concentrations via carbohydrate ingestion during exercise, due to first-pass extraction of glucose by the liver, counterregulatory mechanisms, and/or limitations imposed by the gut.

The question therefore isn’t, what’s the optimal plasma glucose concentration, but rather, what’s the optimal rate of carbohydrate ingestion, something that we already have a reasonably good handle on.

The second part of the question is therefore the more important one, at least if you’re a CGM manufacturer and want to widen your market. I wouldn’t say that it is AN important question, though.

(My litmus test: will it play in Peoria, i.e., is it NIH fundable?)

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it’s basically the whole thing. it’s a little repetitive. the lady on there has a private practice and she said she has seen her patients who get CGMs will over-react and completely stop eating carbs. then she talks about how important it is to feel signals from your body and not overinterpret CGM data.

she also seems super frustrated with some of these companies and social media influencers who push these things with a profit > health mentality. she said she would like them policed basically but acknowledges there’s no real way to do that.

probably meant more for newbies like me than someone like you. you can listen to this at 1.5x speed and get the gist.

I wore one for 2 weeks as put of the Zoe project here in the UK. I found it fascinating how not only different foods affected my glucose response but also how the order in which you ate protein, fats fibre and carbs altered the response. A friend was using one at the same time and he had completely different responses than I did to some foods .
Part of it involved eating a standard muffin which was supplied and then taking some blood samples after a period of time and sending it off to them for analysis. Apparently for my age (67) I was distinctly average at clearing glucose, however I very bad in absolute terms. (says something about the general metabolic health of the population as we get older). For some strange reason I was very good at clearing fats from my blood both in respect to my age group and the population as a whole. Nor quite sure how to use that last bit.


Profit > Health has been and will always be.

I think there are two camps though, those that believe their own lies, and those that simply don’t care what they are doing to others. There may be a third category that encompasses both.

Really interesting discussion in this thread, thanks. I did think this was perhaps a little unfair on Peter Attia though. Coincidentally, I’ve just read the nutrition chapter in his book and while he’s certainly pro-CGM, he is clear that raised glucose during exercise is no bad thing. He finishes the chapter “I have one final piece of advice. Stop overthinking nutrition so much. Put the book down. Go outside and exercise.”

I haven’t read/listened to any of his other stuff, so perhaps the book isn’t representative but I find it fairly clear where the facts stop and the opinion begins and I can make my own judegments from there.

What was unfair in your view?
I encountered him when I tried learning about nutrition and improving my lifestyle. I learnt to be very, very cautious when it came to advice given by people like him.

I am a researcher by trade and found learning about nutrition (as a non-expert) to be a minefield. Most books (aimed at a general audience) about nutrition want to sell their take on what “the right diet/way of life” is.

A few common factors that trigger my skepticism are:

  • Focus on one particular mechanism or e. g. micronutrient, and then extrapolation on general health outcomes. There is no way for non-experts to judge the validity of these arguments and usually research that links microscopic processes to macroscopic health outcomes are scarce. I reckon that even for experts it is often hard.
  • Some influencers (for the lack of a better word) are quacks and just spout BS. But others are much more subtle, and they package things you should be very skeptical of in a stream of reasonable ideas.
  • Subtle misguided appeals to common sense. E. g. should glucose levels in diabetics be comparable to those of athletes while exercising? I’m not qualified to answer that question, others in this thread are. But I’d be cautious to anyone implicitly or explicitly claiming they should be.
  • Prominent use of MD or PhD in their videos, websites and material without (currently or ever) doing research on that topic. You could be a nephrologist and have little clue about nutrition. Or I could record videos on nutrition and use my PhD (in mathematical physics) to impress people.
  • People have something for sale (courses, books, etc.) and their podcast is promotional material.
  • Lack of perspective. My understanding (as a non-expert) is that regular exercise, good, regular sleep and a reasonably healthy diet have much more impact than e. g. making sure you get 2x the dose of micronutrient X or cut out red meat. My observation is that a lot of people will focus on marginal gains while leaving a lot of big gains on the table.
  • Lack of humility on the side of the speaker: usually, we know surprisingly little with great certainty. And the more specific the question, the less we tend to know.
  • Listeners should stay humble: I am not qualified to adjudicate the scientific disagreement in this thread. That doesn’t mean I don’t have an opinion on who is likely to be right. But I don’t think it makes sense for non-experts to dive in too deeply without having had years of experience under their belt.

I don’t want to single out Attia. And some of these factors in isolation need not completely disqualify someone. E. g. TR’s podcast is certainly also marketing. But TR is transparent about it and you, the listener, can and should apply more skepticism to claims that are related to TR’s business.

What helped me was to not listen to one particular person and instead try and listen to recurring themes.


Oh, I don’t disagree with any of your points, just that in my reading of the book, particularly on nutrition, I don’t think he does the things you are complaining about. My take away so far is to eat a balanced diet consisting of whole foods, make sure you get enough protein, avoid fructose-containing drinks and ensure you do enough exercise to burn the calories you consume. He would recommend CGM for a couple of months, I think mainly to push you towards the above diet. I would be interested to try it myself, though I’m not sure I’m going to stump up the cash.

Now, I’ve never listened to his podcast, or read anything else he’s written, so I am basing this entirely on Outlive. Perhaps this is not representative of the rest of his output.

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To be fair, while I do remember his name from my research a few years back, I no longer remember where I thought back then he fell on the spectrum. Others I still remember (e. g. Dr. Eric Berg) stuck in my mind as being egregious.

It certainly wasn’t meant as a definitive judgement on Attia, and I apologize if it came across this way. Also, even if some people hold some controversial opinions in some areas, it does not mean everything they say or claim needs to be.

what I can say as a Type 1 Diabetic: My average early morning glucose is much (!) lower during consistent endurance training weeks than during rest weeks etc.
My average insuline intake during training weeks is also much lower.
Go figure the effect of endurance training on the body’s average glucose level


To follow up on this, there’s an excellent in depth discussion on Inside Excercise podcast this week. And there, they do name and shame Peter Attia for this relating to a study commentary on his blog. Spotify