Short sleep duration is associated with insulin resistance independent of adiposity in Chinese adult twins

Objective: To investigate the association between sleep duration and insulin resistance in rural Chinese adults and examine whether any such associations are independent of adiposity. Methods: This is a cross-sectional analysis of 854 men and 640 women aged 20 to 70 years from the Anqing Twin Cohort. The following measures were obtained for each subject: Body mass index (BMI) and percentage of trunk fat (%TF), fasting plasma glucose, homeostatic model assessment of insulin resistance index (HOMA-IR), self-reported sleep duration and measures of snoring and sleep disturbance from the Pittsburgh Sleep Quality Indices (PSQI) questionnaire were modified for a Chinese population. Multivariate linear regressions were applied to examine the association of sleep duration with HOMA-IR, with and without adjustment for adiposity variables, along with other relevant covariates. Results: In this sample of relatively lean rural Chinese adults, short sleep duration was associated with HOMA-IR in women but not in men. In women, short (≤7 h/night) sleep duration was associated with a higher HOMA-IR (p= 0.003) compared with normal sleep duration (>7 to ≤8 h/night) after adjustment for all the covariates except adiposity. Further adjustment for BMI or %TF attenuated the sleep-HOMA-IR association, but the association remained significant upon adjustment for BMI (p= 0.013); and upon adjustment for %TF (p= 0.026). Long sleep duration (>8 h/night) was not significantly associated with HOMA-IR. Conclusion: In this rural Chinese cohort, short sleep duration is independently associated with increased insulin resistance among women only, even after adjusting for adiposity and other potential confounders.