The purpose of this study was to investigate the association between coffee intake and incident diabetes based on an oral glucose tolerance test (OGTT) and examine coffee habits in those with impaired glucose separately from those with normal glucose at baseline.
In this prospective study, 910 adults aged >/=50 years without diabetes at baseline in 1984-1987 were followed to 1992-1996, an average of 8 years after assessment of coffee intake. Logistic regression models were adjusted for sex, age, physical activity, BMI, smoking, alcohol, hypertension, and baseline fasting plasma glucose.
Past and current coffee drinkers had a reduced risk of incident diabetes (odds ratio 0.38 [95% CI 0.17-0.87] and 0.36 [0.19-0.68], respectively) compared with those who never drank coffee. The 317 participants with baseline impaired glucose who were past or current coffee drinkers were also at reduced risk for incident diabetes (0.31 [0.11-0.87] and 0.36 [0.16-0.83], respectively).
This study confirms a striking protective effect of caffeinated coffee against incident diabetes and extends these findings to incident diabetes based on OGTT independent of multiple plausible confounders.