Shorter Sleep Duration is Associated with Decreased Insulin Sensitivity in Healthy White Men

Study Objective: Short sleep has been linked to increased risk for type 2 diabetes and incident cardiovascular disease and acute sleep restriction impairs insulin-mediated glucose disposal. Here, we examined whether indices of glucose metabolism vary with naturally occurring differences in sleep duration. Design and Measures: Subjects were midlife, nondiabetic community volunteers (N = 224; mean age 44.5 +/- 6.6 y [range: 30-54]; 52% female; 89% white). Laboratory measures of insulin sensitivity (Si) and acute secretion (AIRg), glucose effectiveness (Sg), and disposition index (Di) were obtained from a 180-min, intravenous glucose tolerance test. Results: Shorter self-reported sleep duration (in hours) was associated with lower Si (P = 0.043), although an interaction of sleep duration with participant race (beta = -0.81, P = 0.002) showed this association significant only in whites. Moreover, sex-stratified analyses revealed that shorter sleep duration predicted lower Si in white men (beta = 0.29, P = 0.003) but not in white women (P = 0.22). Findings were similar for AIRg. The relationship between sleep duration and AIRg was moderated by race as well as sex, such that shorter sleep duration associated with greater insulin release only in white men (beta = -0.28, P = 0.004). Sleep duration was unrelated to Sg and Di (P's > 0.05). Conclusions: Our findings suggest that shorter sleep duration may impair insulin sensitivity and beta-cell function in nondiabetic white men, possibly contributing to later type 2 diabetes and cardiovascular disease.