Rice intake and type 2 diabetes in Japanese men and women: the Japan Public Health Center-based Prospective Study

BACKGROUND: Refined carbohydrates have been suggested to deteriorate glucose metabolism; however, whether persons with elevated intakes of white rice, which is a major staple food for the Japanese, experience increased risk of developing type 2 diabetes remains unclear. OBJECTIVE: We prospectively investigated the association between white rice intake and risk of type 2 diabetes. DESIGN: Participants were 25,666 men and 33,622 women aged 45-75 y who participated in the second survey of the Japan Public Health Center-based Prospective Study and who had no prior history of diabetes. We ascertained food intake by using a validated 147-item food-frequency questionnaire. Odds ratios of self-reported, physician-diagnosed type 2 diabetes over 5 y were estimated by using logistic regressions. RESULTS: A total of 1103 new cases of type 2 diabetes were self-reported. There was a significant association between rice intake and an increased risk of type 2 diabetes in women; the multivariate-adjusted odds ratio for the highest compared with lowest quartiles of rice intake was 1.65 (95% CI: 1.06, 2.57; P for trend = 0.005). In men, the association was unclear, although there was a suggestion of a positive association in persons who were not engaged in strenuous physical activity (P for trend = 0.08). CONCLUSIONS: Elevated intake of white rice is associated with an increased risk of type 2 diabetes in Japanese women. The finding that is suggestive of a positive association of rice intake in physically inactive men deserves further investigation.