I have a patient with normal A1c and lipids, diabetes in family, started monitoring blood sugar because she’s having easy weight gain, especially with starchy carbs and difficult weight loss. Blood sugar throughout the day pre- and post-prandial is okay on a low-moderate-carb diet. However, she’s fasting for 14 hours at night, and morning readings are high, in the 108 range, and can rise before eating. She had black coffee, and blood sugar rose from 108 to 114 an hour later, no food yet. Comments on the high a.m. readings and if coffee can raise levels significantly.

Chris Kresser:  First of all, an increase of 108 to 114 is not statistically significant interindividually, especially if that’s being measured with a glucometer, since they’re notoriously inaccurate. I mean they’re not—how should I put it?—they’re not, it’s not advisable with that level of precision. In other words, you can’t expect to detect a difference that small precisely using a glucometer. When we talked about blood sugar, I mentioned that they should be used more for detecting patterns rather than looking at specific values like that from one to the next because they’re just not accurate enough for that. Even the international standard, the new one that’s been proposed, is plus or minus 10 percent. So if you did a plus or minus 10 percent from 114, that means the actual blood sugar if you measured it, if they went into a lab and had it measured, could be anywhere from 100 to 128. So we can’t really draw conclusions with these specific values from moment to moment. In terms of the question of someone who has high fasting blood sugar in the morning with all other markers normal, I believe we talked about this little bit in the blood hyperglycemia unit, but there’s something called the dawn effect that some people experience where their fasting blood sugar goes up. If they’re on a lower-carb diet, their cellular energy needs are met by fat and so they become mildly physiologically insulin resistant to sugars overnight and then when they wake up in the morning, their fasting blood sugar is slightly elevated. But as soon as they eat, it drops down. And one way that you can test that is you could have them increase their carbohydrate intake, you could also have them eat earlier in the morning or eat just before bed and see if that changes the situation. And then you could use the True Health Diagnostics panel with the diabetes prevention and management section to get some more advanced blood sugar markers that have been shown to be earlier indicators of the progression toward type 2 diabetes than some of the markers that are available on the basic blood panel.