What is the effect of caffeine on blood sugar? I drink about 4 cups of black coffee a day.

Amy Campbell


Several small studies have shown that caffeine may raise blood glucose levels in people with type 2 diabetes. In a study done at Duke University, 10 people with type 2 diabetes who regularly drank four cups of coffee each day were given 250 milligrams (mg) of caffeine at breakfast and another 250 mg of caffeine at lunch. On another day, the subjects got placebo pills which contained no caffeine. On the days that the subjects got the caffeine pills, their blood glucose levels were 8 percent higher than on the placebo days, plus, their blood glucose levels spiked higher after meals as well. Of course, this was a very small study, but the results are interesting. There are other studies that indicate that decaf coffee may actually help people better manage their blood glucose. If you think caffeine may be affecting your blood glucose, try cutting back (but not cutting out) coffee for a few days and check your blood glucose a few times a day with your meter. See if you notice lower readings. If you do, you might consider limiting your coffee intake, or drinking decaf coffee in place of some of your regular coffee.

2 replies

Fairlawngirl 2012-01-23 10:11:20 -0600 Report

I was a pediatrician, was working an ER shift, and checked my BS due to my symptoms. I was going to finish my shift, but the ER folks made me go to an adult ER

Fairlawngirl 2012-01-23 10:10:06 -0600 Report

Thanx for indicating the smallness of the study. I would not think that is true for us. I have difficult to control diabetes, despite counting carbs like crazy and being on a pump.
It is very much stress related. Lately, I have been using subq injections to help the high ones!