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Caffeine Effects on Blood Sugar and Insulin



Hello! I wanted to know if drinking coffee affects blood sugar and insulin levels. Also, is caffeine bad for diabetes?


It has not been my impression that there is much effect one way or the other of caffeine-containing beverages/foods in diabetes but your question prompted me to carry out a literature search. I came across a recent scientific paper which demonstrates that a high dose of caffeine taken in the form of a pill can cause an increased awareness of hypoglycemia (low blood sugar) under experimental circumstances. Apart from that, it does not appear to have an effect on blood sugar control. One of the other areas of concern for people with diabetes is the issue of coffee and heart attacks. On balance, studies over the last 25 years appear to indicate that coffee probably has either a small effect or no effect on the risk of heart attacks. Does the hypoglycemia study result mean that coffee might be helpful in people who have problems detecting when their blood sugars are low? The study certainly raises that as a tantalizing question but unfortunately does not answer that under real life conditions. For those who face the problem of difficulty sensing when your blood sugar is low and do not have problems with needing to limit fluid intake, however, there may be little risk in testing whether increasing coffee intake improves how well you detect hypoglycemia. Don`t rely on something like this however until you have very convincing evidence that it works for you. For those interested, the reference for the paper is: Watson JM, et al. Influence of caffeine on the frequency and perception of hypoglycemia in free-living patients with type 1 diabetes. Diabetes Care 2000 Apr;23(4):455-9.

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Response by:

Robert M Cohen, MD Robert M Cohen, MD
Professor of Clinical Medicine
College of Medicine
University of Cincinnati