Caffeine impairs insulin action, but doesn't necessarily affect blood sugar (glucose) levels in young, healthy adults. However, if you have type 2 diabetes, the impact of caffeine on insulin action may be associated with a small, but detectable rise in blood sugar levels, particularly after meals. About 250 milligrams of caffeine — or the equivalent of 2 to 2 1/2 cups (473 to 591 milliliters) of plain, brewed coffee — a day may cause this effect.
If you have type 2 diabetes and you're struggling to control your blood sugar levels, limiting the amount of caffeine in your diet may provide a benefit.
Apr. 04, 2012
- MacKenzie T, et al. Metabolic and hormonal effects of caffeine: Randomized, double-blind, placebo-controlled crossover trial. Metabolism. 2007;56:1694.
- Lane JD, et al. Exaggeration of postprandial hyperglycemia in patients with type 2 diabetes by administration of caffeine in coffee. Endocrine Practice. 2007;13:239.
- Tunnicliffe JM, et al. Coffee, glucose homeostasis, and insulin resistance: Physiological mechanisms and mediators. Applied Physiology, Nutrition and Metabolism. 2008;33:1290.
- USDA National Nutrient Database for Standard Reference, Release 24. U.S. Department of Agriculture. http://ndb.nal.usda.gov/. Accessed Jan. 31, 2012.
- Moisey LL, et al. Caffeinated coffee consumption impairs blood glucose homeostasis in response to high and low glycemic index meals in healthy men. American Journal of Clinical Nutrition. 2008;87:1254
- Greenberg JA, et al. Decaffeinated coffee and glucose metabolism in young men. Diabetes Care. 2010;33:278