Longer sleep duration is associated with diabetes mellitus among older adults with impaired fasting glucose

Abstract

Introduction: Suboptimal sleep duration and quality are associated with increased risk of diabetes mellitus (DM) in the general population. It is uncertain how age-related changes in sleep patterns impacts DM risk in the older population. This study investigates the association between sleep patterns and DM among older adults with impaired fasting glucose (IFG) in Hong Kong. Methods: A cross-sectional study in patients aged >40 years with previously diagnosed IFG, and recruited from generalout-patient-clinics were conducted. Sleep duration and quality was assessed by the Pittsburgh Sleep Quality Index (PSQI), which measures overall sleep pattern including subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbances, use of sleep medication, and daytime dysfunction. DM was defined by: fasting glucose level ≥7 mmol/L, 2-hour-post-challenge glucose level >11 mmol/L after a 75-gram oral glucose tolerance test, or haemoglobin A1c ≥6.5%. The associations between sleep pattern and risk of DM were examined by multivariable logistic regression adjusted for age, gender, anthropometry, lifestyle factors, presence of comorbidities, blood pressure and lipids. Results: Patients (n=401, mean age 67.0 ± 7.5 years, 49.8% male) had an average sleep duration of 6.3 ± 1.4 hours and PSQI score of 6.3 ± 4.4. Overall, 28.9% and 6.7% of patients had DM and obstructive sleep apnea, respectively. After adjusting for covariates, the odds of DM increased by 29% (OR 1.29, 95%CI [1.06,1.56]) for every hour increase in sleep duration. Patients with ≥8 hours of sleep had significantly greater odds of DM (OR 2.50, 95%CI [1.16,5.39]) than those with <6 hours. No significant associations were observed for other PSQI components. Conclusions: Longer sleep duration is associated with greater DM odds among older adults with impaired fasting glucose; conventional guidelines for optimal sleep duration may not apply in high risk groups. Future studies should include objective measures to describe sleep patterns associated with DM risk.