Longer sleep duration and the incidence and progression of diabetic nephropathy: a prospective cohort study

BACKGROUND: Sleep duration has been linked to adverse health outcomes, but its association with diabetic nephropathy remains unclear. OBJECTIVE: This study aimed to assess the association between sleep duration and a composite endpoint of incidence and progression of diabetic nephropathy. METHODS: The study participants were 678 Japanese outpatients with type 2 diabetes. Lifestyle habits were assessed at baseline and at years 2 and/or 5. Mean values of lifestyle factors were calculated by averaging measurements from baseline to the date of endpoint onset or the end of follow-up. A multivariable Cox proportional hazards model was used. RESULTS: During a follow-up of 6.0 ± 2.7 years, 215 participants experienced the endpoint. Among lifestyle factors, mean sleep duration was the only factor associated with the endpoint. Compared with participants sleeping <6 hours, the multivariable-adjusted hazard ratios for mean sleep duration of 6 to <7, 7 to <8, and ≥8 hours were 1.08 (95% CI, 0.74-1.57), 1.56 (95% CI, 1.05-2.31), and 1.92 (95% CI, 1.15-3.19), respectively (P for trend = .003). This association remained significant after adjustment for key lifestyle and diabetes-related factors. The association was stronger in older participants and those with microalbuminuria or reduced kidney function. CONCLUSION: Longer, but not shorter, sleep duration is associated with an increased risk of incidence and progression of diabetic nephropathy.