Abstract
OBJECTIVES: We aimed to assess the associations between night-time sleep duration and fasting glucose (FG), triglyceride (TG) to high-density lipoprotein cholesterol (HDL-C) ratio and body mass index (BMI) among adults free of type 2 diabetes (T2D) or without diagnosed T2D. DESIGN: Cross-sectional study. SETTING: Medical examination centres at six hospitals in Beijing-Tianjin-Hebei region, China. PARTICIPANTS: Participants were recruited via multistage, stratified cluster sampling. We included adults free of T2D or without diagnosed T2D who attended for physical examination and completed the validated questionnaire. 32 497 participants were included in the study, of whom 52.50% were men. PRIMARY AND SECONDARY OUTCOME MEASURES: FG, TG, HDL-C, height and weight were measured. RESULTS: Overall, 12.80% and 9.67% reported night sleep duration <7 hours and ≥9 hours, respectively; 6.91% had elevated FG and 3.57% had undiagnosed T2D. Sleep duration had an independent, U-shaped associated with FG (β(1) (linear term)=-0.111, p=0.047; β(2) (quadratic term)=0.008, p=0.026) with 6.9 hours of sleep associated with the lowest FG and a negative association with BMI (β=-0.154, p<0.001). BMI mediated a U-shaped association of sleep duration with TG/HDL-C (β(1)=-0.040, p=0.017; β(2)=0.003, p=0.023). CONCLUSIONS: Both short and long night-time sleep was associated with elevated FG, and short sleep duration was associated with increased BMI. BMI mediated a U-shaped association between sleep duration and TG/HDL-C.