[00:00] Real Madrid fans notice the players wearing a mysterious white disc on their arms. There was a lot of speculation. Are those fitness trackers? Are they heart function monitors?
[00:12] Those are actually continuous glucose monitors, or CGMs, and what they revealed during a Champions League game, no less. Really surprise scientists, including me, and it's going to
[00:24] completely change how you think about blood sugar. Because in a different context, the numbers from those players would look like diabetes. Scientists set out to study 18
[00:36] rheumatoid players, and they tracked their glucose level, their sugar level in their body, continuously for two weeks, including during a Champions League match. Here's what they found. During the game, the active players, the ones that were actually playing for at least 12 minutes or more,
[00:53] they averaged 159 milligrams per desk leader of glucose. Just for context, in a fasting, resting individual, this level would be in the diabetic range. And several players
[01:06] hit much higher between 180 and 200 milligrams per desk leader. The reserve players, the players that were mostly on the bench, they averaged 133. Now, here's an important caveat. These devices,
[01:20] the CGMs, they don't measure glucose levels in the blood. They measure sugar glucose right under the skin. It's what we call interstitial fluid. It's the liquid between the cells, so they're really useful to show patterns over time, and they mirror sugar levels in the blood.
[01:37] But there's a bit of a gap. There's a time gap. They lag behind blood sugar levels by about 15 to 20 minutes, and there's also a bit of a value gap. Studies have estimated this, and the CGM can
[01:52] overestimate blood sugar levels by about 16 points. So instead of 159, their average in the blood might actually be in the 140s, and those high values might actually be in the 170s instead of
[02:07] 190 or so, right? Which still surprised me. I did not expect the values to be that high. And the other thing is these weren't transient values. They weren't quick peaks of sugar going up, and quickly
[02:21] coming back down. You can see on the graph, players kept those high values during most of the game, and even after the game, it took a while for it to come back down. Now, here's an important question, where the player is drinking a bunch of gatorade with a lot of sugar in it, or were they eating a lot
[02:36] of snacks during the break with a lot of carbohydrates, and is that why the sugar levels are so high? Fortunately, the researchers thought of all this, and they explained in the study, the last meal was about three and a half hours before the game. So they weren't completely fasted,
[02:50] but they had eaten right before the game. This is what you would expect. And they typically did not supplement with additional carbohydrates during the game, including sports drinks and energy gels.
[03:02] Most of the players report drinking only water. So why do we see these high glucose levels higher in the players that are playing compared to the bench players, even though there's not more carbohydrates, more sugar going in. Well, exercise triggers stress hormones like cortisol and adrenaline,
[03:21] and those can spike your glucose. They can cause your liver to produce and pump more glucose into your bloodstream. So here's the key realization. If I had one of these readings when I'm fasted
[03:35] and sitting down, that would be incredibly alarming because that would indicate diabetes. But in these young, highly fit elite athletes during competition, intense exercise, at the highest level,
[03:49] these values appear to be completely normal physiology. And this is the mistake that a lot of people make when they interpret their own blood sugar values. A higher value after a meal, for example, when we sometimes call a spike doesn't mean disease. It doesn't mean you have diabetes. It's all
[04:07] about the context. High sugar levels when you're fasted and resting. Yes, that's a concern. But an increase in glucose after eating, for example, or during or after exercise, completely normal physiology.
[04:20] That's just like blood pressure and heart rate, by the way. If it's chronically high, at rest, all the long you're exposed to high blood pressure or high heart rates concern.
[04:32] But if it's temporarily elevated during a specific stimulus, like exercise, for example, that it's a normal physiological response, not a concern. So that is the key difference between
[04:44] understanding your glucose data, your CGM data, and completely misreading it. If you want to understand your blood sugar changes, are they normal or should you be concerned? We have a full deep dive
[04:56] in this video right here. Check it out. And please share this video with a friend who wears a CGM and panics every time they see a blood sugar spike.