Should you avoid coffee since it increases blood sugar?
As a type 1 diabetic, making sure my blood sugar is in a safe range is something I have to monitor every day, so when I read that coffee increases blood sugar levels, I wanted to know how much it increased my blood sugar. To find out how much drinking iced coffee increased my blood sugar, I tested my blood sugar before eating or drinking anything (except plain water) with my glucose monitor (I prick my finger and put the small drop of blood on a test strip), and after drinking iced coffee (just refrigerated coffee, water, and ice). I used a food scale to weigh the coffee to make sure it was the same amount each time. I did several tests to see if there was a pattern.
- Test 1: 5 oz of coffee increased my blood sugar by 3 points
- Test 2: 6 oz of coffee increased my blood sugar by 36 points
- Test 3: 5 oz of coffee increased my blood sugar by 2 points
- Test 4: 5 oz of coffee increased my blood sugar by 16 points
- Test 5: 5 oz of coffee increased my blood sugar by 14 points
- Test 6: 5 oz of coffee increased my blood sugar by 13 points
As you can see from the above numbers, there is no consistency, and there is no way to predict how much plain coffee will increase my blood sugar. I accidentally poured an additional ounce of coffee on test two, which increased my blood sugar levels higher compared to the other tests, but glucose monitors are not 100% accurate, and can be off by 10%, either upwards or downwards. For instance, I have tested my blood sugar three times in one minute, and each time, the numbers will be different (but not typically that far off from each other).
I decided to throw test two out, but still disclose it, because the amount of coffee was higher than the other tests, and because it appears to be an anomaly. Another factor to take into consideration is how stressed I was on the day I took those tests, because stress increases blood sugar levels (especially for diabetics). By averaging the numbers over five of the six tests, blood sugar increased by approximately 10 points. Since that is not a significant increase, I don’t think it’s anything to be concerned about for me, but for someone who is pre-diabetic, or diabetic, and drinks more than five ounces of coffee, which is a very small amount, I would advise them to test their blood sugar before and after like I did, preferably over a longer period of time, maybe two weeks, to see how coffee affects their blood sugar levels, since everyone reacts differently.
If coffee increases someone’s blood sugar by 50 points, avoiding coffee, or taking prescribed blood sugar lowering medication, or exercising shortly after drinking coffee is what I would suggest, along with talking to your doctor about the best method to take to keep your blood sugar from spiking.