OSAKA, Japan--Consuming caffeine via green tea or coffee appears to reduce the risk of developing type 2 diabetes in Japanese adults, according to a new study from the Annals of Internal Medicine (144, 8:554-62, 2006). In the retrospective cohort study, conducted on 17,413 adults in 25 communities across Japan, researchers examined consumption of coffee; black, green and oolong teas; and diagnosed type 2 diabetes over a five-year follow up. Consumption of green tea and coffee was inversely associated with risk of developing diabetes after adjustment for risk factors including body mass index (BMI), age and sex; consuming greater than six cups of green tea or three cups of coffee reduced the risk by 33 percent and 42 percent, respectively. There was no association seen between consumption of black or oolong teas and diabetes risk. Total caffeine intake from these beverages was associated with a 33-percent reduced risk for diabetes, with the effects more pronounced in women and in overweight men.