Caffeine & Insulin

Researchers have studied the effects of caffeine, alone and in coffee and tea, for its effects on insulin and blood sugar. While the evidence is mixed, several studies suggest that caffeine may contribute to insulin resistance and glucose intolerance, which in turn raise the risk of type 2 diabetes. However, several population studies indicate that routinely drinking coffee and/or tea --- with or without caffeine --- may reduce your risk of diabetes.

Insulin

Insulin is a major hormone your body produces to metabolize carbohydrates and fats. Your digestive system breaks down food into glucose, or sugar, which your body uses for energy. After you eat, the level of glucose in your blood rises, and your pancreas produces insulin to help the cells absorb and use glucose.

Insulin Resistance

If your body's sensitivity to insulin decreases, you can develop insulin resistance, meaning your muscle, fat and liver cells don't respond as they should to insulin, and your body needs more and more of the hormone. Eventually, your pancreas can't keep up with your body's demand for insulin, and glucose builds up in your blood, making you a prime candidate for diabetes. A variety of factors boost your risk for insulin resistance, including genetics, being overweight and physical inactivity. Researchers also have been studying how various foods affect insulin.

Caffeine

A small, placebo-controlled study in the Netherlands showed that caffeine could decrease the body's sensitivity to insulin, as reported in the February 2002 issue of "Diabetes Care." Later studies have produced similar results. In the December 2007 issue of Metabolism, Dartmouth Medical School researchers reported that in a randomized, placebo-controlled study, taking 200 mg of caffeine twice a day in capsule form reduced insulin sensitivity in healthy adults.

Coffee

On the other hand, several population studies in the United States, Europe and Japan have suggested that habitual coffee and tea drinkers have a lower risk of getting type 2 diabetes --- in fact, it seems that the more coffee you drink, the less likely you are to get the disease. In a review of the evidence published in the December 14-28, 2009 issue of the "Archives of Internal Medicine," Australian researchers reported that regular coffee, tea and decaffeinated coffee all are associated with a reduced risk of type 2 diabetes.

Conclusions

Coffee is a complex blend of many substances besides caffeine, including potassium, niacin, magnesium and various antioxidants. In a review published in the January 2006 journal "Nutrition, Metabolism and Cardiovascular Disease," a Harvard nutrition researcher wrote that habitual consumption of both caffeinated and decaffeinated coffee have been associated with a lower risk of diabetes, suggesting that components in coffee other than caffeine help ward off the disease. Like many other health experts, he also pointed out that, coffee drinking aside, managing your weight and staying physically active play the biggest roles in preventing type 2 diabetes.