Study: Drinking Coffee Reduces Type-II Diabetes Risk

If drinking coffee will reduce type-II diabetes risk, my risk should be in negative numbers.

The study, by Dr. Rob M. van Dam and colleagues at the Harvard School of Public Health in Boston, Massachusetts, is part of a new Nurses Health Study II--a prospective cohort study. The study will be published in the February issue of Diabetes Care, a journal of the American Diabetes Association.

Researchers followed 88,259 U.S. women ages 26 to 46 without diagnosed diabetes and monitored their consumption of coffee and other caffeine-containing foods and drinks in 1991, 1995, and 1999. Over the first ten years of the study, 1,263 cases of type-II diabetes were recorded.

Drinking coffee was associated in a dose-response fashion with a decreased risk of type 2 diabetes. One cup of coffee a day was linked with a 13 percent reduction of type 2 diabetes risk compared with 42 percent reduction for two to three cups a day, and 47 percent reduction for four or more cups a day.

Associations were similar for caffeinated (13 percent reduction) for a one-cup increment per day and decaffeinated (19 percent) coffee and for filtered (14 percent) and instant (17 percent) coffee.

However, tea consumption was linked only with a 12 percent lower risk in those who drank four or more cups risk of type 2 diabetes, indicating that caffeine is not the major constituent that affects the risk.

Not all types of coffee have the same effect. The reduction of type 2 diabetes risk was found with drinking filtered coffee and instant coffee, but not with consumption of espresso or percolator coffee.

Researchers conclude that" moderate consumption of both caffeinated and decaffeinated coffee may lower risk of type 2 diabetes in younger and middle-aged women. Coffee constituents other than caffeine may affect the development of type 2 diabetes."

An earlier study, published in 2004 in the Annals of Internal Medicine, had shown a 30 percent reduction of diabetes risk in women who drank more than six cups of coffee a day.

For men, drinking six or more cups of caffeinated coffee was also linked with a 30 percent lower risk.

That study, by Frank Hu and colleagues from the Department of Nutrition and Epidemiology at the Harvard School of public Health, tracked some 41,934 men from 1986 to 1998 and 84,276 women from 1980 to 1998 for their intake of regular and decaffeinated coffee via food frequency questionnaires every two to four years. Subjects entered the study without known type 2 diabetes. The study did not consider other risk factors.

Caffeine has been shown to have negative effects on glucose metabolism, so there must be some other factor involved, which would explain why decaf coffee produces almost as much risk reduction. So if you are sensitive to caffeine, go with the decaf and enjoy protection from diabetes without the jitters.