Coffee, Decaffeinated Coffee, and Tea Consumption Linked to Lower Diabetes Risk

The meta-analysis included data obtained from 18 studies that reported on the association between coffee consumption and diabetes; six studies that reported estimates of the association between decaffeinated coffee and diabetes; and seven studies that reported on the association of tea.

The results of the pooled meta-analysis found that drinking coffee was inversely related to risk of diabetes (more coffee was linked to lower risk). After adjusting for potential confounders, every extra cup of coffee consumed in a day was linked to a 7% reduction in the excess risk of diabetes; drinking 3 to 4 cups per day was linked to a 25% lower risk than drinking none or up to two cups per day. In those studies that assessed decaffeinated coffee consumption, drinking more than 3 to 4 cups a day was linked to about one third lower risk of diabetes, compared to none. Drinking more than 3 to 4 cups of tea per day was linked to a one fifth lower risk of diabetes, compared to non-tea drinking. The authors suggested the effect of tea and coffee consumption on diabetes risk could be due to direct biological effects, since their apparent protective effect appears to be independent of potential confounding variables, and could partly be due to other compounds present in tea and coffee, such as magnesium, or antioxidants such as lignans or chlorogenic acids. The study was published in the December 14, 2009, issue of the Archives on Internal Medicine.

"If such beneficial effects were observed in interventional trials to be real, the implications for the millions of individuals who have diabetes mellitus, or who are at future risk of developing it, would be substantial,” concluded first author Rachel Huxley, M.D., of the George Institute, and colleagues. "It could also be envisaged that we will advise our patients most at risk for diabetes mellitus to increase their consumption of tea and coffee in addition to increasing their levels of physical activity and weight loss.”

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George Institute for International Health
University of Glasgow