Association of poor sleep quality with adverse glycaemic outcomes in Chinese Itadults with type 2 diabetes: a family-based cohort study.

OBJECTIVES: To examine the association between baseline sleep quality and subsequent glycaemic outcomes in adults with type 2 diabetes mellitus (T2DM), using repeated fasting blood glucose measurements and longitudinal glycaemic pattern analyses. DESIGN: Prospective cohort study. SETTING: The Taizhou Diabetes Family-based Cohort in Zhejiang Province, China. PARTICIPANTS: A total of 1421 adults with T2DM with baseline sleep quality assessment and follow-up fasting blood glucose measurements were included. MAIN OUTCOME MEASURES: Baseline sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI). Follow-up fasting blood glucose measurements were obtained through 30 June 2025. The primary outcomes were continuous fasting blood glucose levels and binary fasting blood glucose status defined as ≥7.0 mmol/L during follow-up. Secondary outcomes included glycaemic variability and latent glycaemic trajectory classes. RESULTS: Poorer baseline sleep quality was associated with less favourable glycaemic outcomes during follow-up. In the fully adjusted model, each 1-point increase in PSQI score was associated with a 0.096 mmol/L higher fasting blood glucose level (95% CI 0.081 to 0.111), and poor sleep quality was associated with a 0.669 mmol/L higher fasting blood glucose level (95% CI 0.547 to 0.791). For the binary outcome, each 1-point increase in PSQI score was associated with higher odds of fasting blood glucose ≥7.0 mmol/L (OR 1.10, 95% CI 1.08 to 1.12), and poor sleep quality was associated with 1.61-fold higher odds of fasting blood glucose ≥7.0 mmol/L (95% CI 1.37 to 1.91). Higher PSQI scores were also associated with greater glycaemic variability and higher odds of membership in less favourable glycaemic trajectory groups. CONCLUSIONS: Among adults with T2DM, poorer baseline sleep quality was associated with higher fasting blood glucose levels, poorer glycaemic control, greater glycaemic variability and less favourable long-term glycaemic trajectories. These findings suggest that sleep quality may be a relevant and easily assessable marker for identifying individuals at risk of suboptimal long-term glycaemic management.