Relationship between development of diabetes and family history by gender in Japanese-Americans.

Japanese-Americans are more highly exposed to environmental factors related to diabetes, specifically a westernized lifestyle, compared with Japanese living in Japan. We investigated the relationship between family history and development of type 2 diabetes by gender in the westernized environment. Nine-hundred-and-sixty non-diabetic Japanese-American subjects who underwent the 75 g oral glucose tolerance test were followed for 6.8+/-0.1 years (mean+/-standard error). In a log-rank test, women with a family history showed a significantly higher incidence of type 2 diabetes compared with those without a family history (P=0.018), whereas men showed no significant difference (P=0.25). In a Cox proportional hazards model, the hazard ratio of developing diabetes in men and women with a positive family history were 1.56 (95% confidence interval [CI] 0.81-2.97) and 1.86 (95% CI 1.08-3.19), respectively. This association, which indicated a hazard ratio of 1.79 (95% CI 1.04-3.10), persisted even after adjustment for age, systolic, diastolic blood pressure, triglycerides, HDL-cholesterol, category of normal glucose tolerance (NGT) and impaired glucose tolerance (IGT), body mass index and homeostasis model assessment (HOMA-R) in women. Our findings suggest that even if lifestyle is westernized, a family history of diabetes is an important predictor of type 2 diabetes development especially among women in Japanese-American population.