'Lots of studies have looked at the question of whether coffee drinkers are less likely to develop diabetes. The short answer is yes they are.
But the question remains, why does coffee seem to lower diabetes risk? Is it the caffeine?
Researchers from Harvard wanted to know the answer. They conducted a meta-analysis of 28 prospective studies of coffee with 1,109,272 participants. Follow-up ranged from 10 months to 20 years.
Their results published in the American Diabetes Association journal Diabetes Care confirmed that drinking coffee was inversely associated with the risk of type 2 diabetes. And it's dose dependent. The more you drink, the lower the risk. For one cup a day the relative risk dropped to 92%; for three cups a day, to 79%; and for six cups a day it dropped to 67%.'