Ethnic differences in weight gain and diabetes risk: the Multiethnic Cohort Study

To improve our understanding of excess body weight and risk for diabetes type 2, the study examined the influence of weight change in the Hawaii component, including 78,006 Caucasians, Japanese Americans and Native Hawaiians, of the Multiethnic Cohort Study.

Participants aged 58.5±9.2 years completed a questionnaire at cohort entry (Qx1), including weight at age 21, and a follow-up questionnaire 5 years later (Qx2). After 14 years of follow-up, 8892 incident diabetes cases were identified through self-reports or linkups with the major health plans in Hawaii. Cox regression analysis was applied, stratified by age and adjusted for confounders, to estimate hazard ratios (HRs).

The mean weight gain from age 21 to Qx1 was 10.5±11.0 kg and, between Qx1 and Qx2, 0.8±5.6 kg. Diabetes risk showed a significant dose-response relationship with weight gain from age 21 (P<0.0001). The respective HRs for a weight gain of 5-10 kg and greater or equal to 25 kg were 1.8 (95% CI: 1.7-2.0) and 7.7 (95% CI: 7.1-8.4), while weight loss of greater than 5 kg significantly reduced diabetes risk (HR=0.7; 95% CI: 0.6-0.9). The interaction term of weight change since age 21 with ethnicity was also highly significant (P<0.0001). Compared with stable-weight Caucasians, the adverse effects of weight gain were more pronounced in those of Japanese and Native Hawaiian descent. Weight change between Qx1 and Qx2 conferred a smaller risk.

These findings support the current public-health recommendations for weight control and particularly among ethnic groups at high risk for diabetes.