Glucose spikes in athletes vs everybody else
A lot of athletes I see think their slightly elevated glucose is a sign that they are metabolically unhealthy and maybe at risk of 2 diabetes (T2D) and other chronic diseases. In general, we worry about glucose going up because observational studies do show a relationship between high glucose and risk of diseases like T2D. But these observational studies are done in “average” people. Athletes are not average.
When glucose starts creeping up in “average” people (who, due to complex reasons - mostly our crap obesogenic environment - probably have overweight/obesity, are largely sedentary, probably doesn’t do much - if any - vigorous type exercise, and probably have a diet that that’s high in refined carbs, saturated fat and low in fibre) it’s because bad stuff is happening underneath - a large part of which is insulin resistance. Your “average” person will also have one or more of the following:
Chronically elevated fasting insulin (or at least an insulin that’s beginning to creep up).
Ectopic fat (fats starts to get deposited in places it shouldn’t be, like the liver).
Blood pressure that’s creeping up.
Chronically elevated fasting and/or post-prandial triglycerides.
In this context, elevated glucose is a marker for a lot of bad stuff that’s happening underneath. And it’s all this bad stuff underneath that (to a point*) is the reason why people with the symptom of slightly elevated blood glucose are at risk of T2D, CVD etc.
Conversely, what do we think is causing glucose to go up in athletes? Probably a mix of (depending on type of exercise and other factors) cortisol, epinephrine and other “stress” hormones. In addition, the transient** insulin resistance that happens after vigorous activity (probably due an acute** increase in triglycerides) also plays a role.
Do athletes typically have ectopic fat deposition? No. Elevated insulin? No. High blood pressure? Usually no. Do they have insulin resistance? No, they are usually exquisitely insulin sensitive. Chronically elevated triglycerides? No.
What’s causing the elevated glucose in the “average” person is not what is causing elevated glucose in athletes.
In my opinion (let me be clear this is an opinion based on my reading of the literature), the observational data we have on slightly elevated glucose and disease risk [in" “average” people] are not a useful source to try to understand what slightly elevated glucose means in athletes.
If you are lean, have blood pressure + triglycerides + LDL-cholesterol etc in the healthy range, and you eat a reasonable diet and have no family history of T2D, then there’s a good chance your higher than usual glucose readings are a reflection of the high volume and vigor of the activity you’re doing.
Of course, always check in with a medical doctor who can do a full history and assessment and make sure everything’s ok.
Disclaimer: I am a registered dietitian, not a medical doctor (MD). The information provided on this platform is for educational and informational purposes only and does not constitute medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.