Coffee, tea, and incident type 2 diabetes: the Singapore Chinese Health Study

Background: Increasing coffee intake was inversely associated with risk of type 2 diabetes in populations of European descent; however, data from high-risk Asian populations are lacking as are data on tea intake in general. Objective: We investigated the prospective associations between intakes of coffee, black tea, and green tea with the risk of type 2 diabetes in Singaporean Chinese men and women. Design: We analyzed data from 36 908 female and male participants in the Singapore Chinese Health Study aged 45-74 y in 1993-1998 who had multiple diet and lifestyle measures assessed and then were followed up between 1999 and 2004. We used Cox regression models to investigate the association of baseline coffee and tea intakes with incident type 2 diabetes during follow-up, with adjustment for a number of possible confounding or mediating variables. Results: In multivariate models participants reporting >= 4 cups of coffee/d had a 30% reduction in risk of diabetes [relative risk (RR): 0.70; 95% CI: 0.53, 0.93] compared with participants who reported nondaily consumption. Participants reporting >= 1 cup of black tea/d had a suggestive 14% reduction in risk of diabetes (RR: 0.86; 95% CI: 0.74, 1.00) compared with participants who reported 0 cups/d, and we observed no association with green tea. Conclusion: Regular consumption of coffee and potentially black tea, but not green tea, is associated with lower risk of type 2 diabetes in Asian men and women in Singapore.