Purpose: We evaluated the association between sleep duration and type 2 diabetes in a multiethnic cohort, considering insulin sensitivity (S(I)) and secretion (acute insulin response [AIR]), two important diabetes risk factors.
Methods: Among 900 diabetes-free persons, 146 developed incident type 2 diabetes. At baseline, sleep duration was assessed by self-report and S(I) and AIR by a frequently sampled intravenous glucose tolerance test.
Results: Among non-Hispanic whites and Hispanics, short sleep (<or=7 hours: odds ratio [OR] 2.36; 95% confidence interval [CI] 1.21-3.79 compared to 8 hours) was associated with increased odds of diabetes, adjusting for age, sex, glucose tolerance, clinical site, hypertension, family history of diabetes, smoking, education, and body mass index. Adjustment for S(I) and AIR did not affect short sleep (2.36; 1.11-5.00), but further attenuated the already non-significant association with long sleep (2.15; 0.50-9.30). In African Americans, an opposing pattern was observed, but none of the associations reached statistical significance.
Conclusion: Our study supports the role of short sleep as an independent risk factor for type 2 diabetes in whites and Hispanics. While insulin sensitivity and secretion may explain previously reported associations of long sleep duration with diabetes risk, they do not seem to mediate the effects of short sleep on diabetes.