The Potential Effects of Caffeinated Beverages on Insulin Sensitivity.

Caffeinated beverages, most commonly tea and coffee, may have important effects on insulin regulation that may give their consumption an important role among nutritional factors in the development of diseases of glucose and insulin metabolism, such as diabetes and atherosclerotic vascular diseases. These beverages include compounds that may have contradictory effects on insulin and glucose: Caffeine impairs insulin sensitivity, but polyphenolic molecules within tea, coffee, and cocoa augment the effects of insulin. In addition, epidemiologic associations exist between greater consumption of such beverages and lower risk of diabetes. The beneficial effects of such beverages might be enhanced by changing the process of their preparation and substitution of other substances commonly added to caffeinated beverages that impair the effect of insulin, such as sugar or milk.