Does coffee consumption reduce the risk of developing type 2 diabetes?

Purpose Three recent studies report that coffee drinkers are at reduced risk for type 2 diabetes. The present study expands this analysis by using an oral glucose tolerance test for the diagnosis of type 2 diabetes. Methods In this prospective study, 910 nondiabetic adults aged 50 or older at baseline were followed from 1972 to 1987, for an average of 8 years after the assessment of caffeinated coffee intake. Logistic regression was used to investigate baseline coffee habits and risk of incident diabetes adjusting for sex, age, physical activity, body mass index, smoking, alcohol, hypertension, and baseline fasting plasma glucose. Further analyses were conducted in participants with normal (n = 593) and impaired glucose (n = 317) at baseline. Results Non-diabetic past and current coffee drinkers were at a similar significantly reduced risk for developing diabetes (OR = 0.38; CI: 0.17–0.87; OR = 0.36, CI: 0.19– 0.68; respectively) compared to those who never drank coffee. Participants with baseline impaired glucose who were past (OR = 0.31; CI: 0.11–0.87) or current (OR = 0.36; CI: 0.16–0.83) coffee drinkers were also at reduced risk. Conclusion This study confirms recent findings of a striking independent protective effect of caffeinated coffee against incident diabetes based on clinical diagnosis.