Can coffee reduce the risk of diabetes?

Diabetes is a disease in which the body does not produce or properly use insulin. Insulin is a hormone needed to convert sugar, starches, and other food into energy for daily life. The cause of diabetes remains a mystery, although genetics and environmental factors such as obesity and lack of exercise appear to play roles.

Research suggests that people who drink coffee are less likely to get type 2 diabetes. However, it isn't clear whether the caffeine or some other ingredient in coffee is responsible for its protective effects.

The researchers wanted to see whether there is a link between diabetes and drinking coffee and green, black, and oolong tea. Participants completed a detailed questionnaire about their health, lifestyle habits, and how much coffee and tea they drank. The questionnaire was repeated at the end of the 5-year follow-up period.

When other factors were accounted for, researchers found that the more green tea and coffee participants drank, the less likely they were to get diabetes. People who drank six cups or more of green tea or three or more cups of coffee each day were about one-third less likely to get diabetes. The link was stronger in women than in men. No pattern was seen with black or oolong tea.

More than 80,000 women took part in the Nurses' Health Study. Over 20 years, over 4,800 women developed type 2 diabetes. The researchers found that a combined intake of over 1,200 milligrams of calcium and over 800 units of vitamin D was linked with a 33% lower risk for type 2 diabetes (as compared to women who took much smaller amounts of calcium and vitamin D). The results show that higher doses of vitamin D and calcium help lower the risk for type 2 diabetes in women.