Coffee intake and risk of type 2 diabetes: the Multiethnic Cohort

OBJECTIVE: We evaluated the influence of coffee consumption on diabetes incidence among the Hawaii component of the Multiethnic Cohort (MEC). DESIGN: Prospective cohort. SETTING: Population-based sample residing in Hawaii. SUBJECTS: After exclusions, 75 140 men and women of Caucasian, Japanese American and Native Hawaiian ancestry aged 45-75 years were part of the current analysis. All participants provided information on diet and lifestyle through an FFQ. After 14 years of follow-up 8582 incident diabetes cases were identified using self-reports, medication questionnaires and health plan linkages. Hazard ratios (HR) and 95 % confidence intervals were calculated using Cox regression while adjusting for known covariates. RESULTS: The risk for diabetes associated with total coffee consumption differed by sex (P interaction < 0·0001). Women consuming ≥3 cups of any type of coffee daily had a significantly lower risk (HR = 0·66; 95 % CI 0·58, 0·77; P trend < 0·0001) than those reporting <1 cup/d, whereas the relationship in men was borderline (HR = 0·89; 95 % CI 0·80, 0·99; P trend = 0·09). The same difference by sex was seen for regular coffee consumption, with HR of 0·65 (95 % CI 0·54, 0·78; P trend < 0·0001) and 0·86 (95 % CI 0·75, 0·98; P trend = 0·09) in men and women, respectively. No significant association with diabetes was apparent for decaffeinated coffee in women (HR = 0·85; 95 % CI 0·72, 1·01; P trend = 0·73) or men (HR = 1·07; 95 % CI 0·93, 1·23; P trend = 0·71). Despite small differences by ethnicity, the interaction terms between coffee intake and ethnicity were not significant. CONCLUSIONS: In this multiethnic population, regular, but not decaffeinated, coffee intake was much more protective against diabetes in women of all ethnic groups than in men