While the authors stressed that their findings did not prove that drinking coffee lowers the risk for diabetes, and people should not increase coffee drinking in order to prevent type 2 diabetes, it does further confirm the link between caffeine and glucose tolerance.
A recent Dutch study also identified an association between higher coffee consumption and lower risk for type 2 diabetes mellitus. However it did not distinguish between intake of regular and decaffeinated coffee.
The new US study, published in today's Annals of Internal Medicine (vol 140, issue 1, pp1-8), found a statistically significant protective association between total caffeine intake and type 2 diabetes mellitus and a modest inverse association with decaffeinated coffee consumption.
The data was taken from a study of more than 126,000 men and women who reported their intake of coffee and other caffeinated beverages every two to four years over a period of 12 to 18 years. Thee participants did not have diabetes, cancer, or cardiovascular disease at baseline.
The association of coffee and type 2 diabetes was similar in strength to the association between consumption of tea and risk for diabetes, added the authors.
Coffee's impact on health is a controversial one as it has also been shown to have negative effects, both for a foetus and through raising risk of heart attack. But evidence of its relationship with glucose has merited European funding for a research project, currently underway, while the coffee industry is also hoping that its health benefits could boost profits.