Physical Activity and Risk of Type 2 Diabetes Among Native Hawaiians, Japanese Americans, and Caucasians: The Multiethnic Cohort

Background: Physical inactivity is an established risk factor for diabetes; however, little is known about this association across ethnic groups with different diabetes risk. Therefore, we evaluated the association between physical activity and diabetes and potential effect modification by ethnicity in the Hawaii component of the Multiethnic Cohort. Methods: Participants, aged 45 to 75 years, were enrolled by completing a questionnaire on demographics, diet, and self-reported weekly hours of strenuous sports, vigorous work, and moderate activity. Among the 74,913 participants (39% Caucasian, 14% Native Hawaiian, 47% Japanese American), 8561 incident diabetes cases were identified by self-report, a medication questionnaire, and through health plan linkages. Cox regression was applied to estimate hazard ratios (HR) and 95% confidence intervals (95%CI) while adjusting for known confounders. Results: Engaging in strenuous sports was inversely related to diabetes risk with HRs (4+ hours/week vs. never) of 0.67 (95%CI: 0.57-0.79) in women and 0.80 (95%CI: 0.72-0.88) in men. In stratified analyses, the inverse association was consistent across ethnic groups. The inverse association of vigorous work with diabetes was limited to men, while beneficial effects of moderate activity were observed only in Caucasians. Conclusions: These findings support a role of high-intensity physical activity and ethnic-specific guidelines in diabetes prevention.