Curvilinear associations of sleep patterns during weekdays and weekends with glycemic control in type 2 diabetes: the Hong Kong Diabetes Registry

We aimed to explore the associations of sleep patterns during weekdays and weekends with glycemic control in patients with type 2 diabetes. We examined the association between indices of glycemic control [glycated hemoglobin (HbA(1c)) and fasting plasma glucose (FPG)] and sleep parameters (sleep duration, bedtime, and differences of sleep duration during weekdays and weekends) from adults with type 2 diabetes recruited in a prospective cohort enrolling from hospital medical clinics. Restricted cubic spline regression was used to examine the relationships between the glycemic indices and sleep parameters. Excluding shift workers, a total of 3508 patients enrolled between July 2010 and July 2014 were included in this analysis. Mean age was 53.9 [standard deviation (SD) 8.7] years, and mean disease duration of diabetes was 8.3 (SD 7.1) years. Fifty-nine percentage were men. Mean sleep duration during weekdays and difference of sleep durations between weekdays and weekends were 7.7 (SD 1.3) hours and 0.6 (SD 1.2) hours, respectively. Mean HbA(1c) and FPG were 7.6 (1.5) % and 7.6 (2.5) mmol/L, respectively. Using restricted cubic spline regressions with successive adjustments of potential confounders, sleep duration difference between weekdays and weekends remained significantly associated with both HbA(1c) and FPG in a curvilinear manner. Sleep duration of about 1 h more during weekends when compared to weekdays was associated with beneficial effect in HbA(1c) (-0.13 %, 95 % confidence interval -0.24 to -0.02). In type 2 diabetes, regular sleeping habit with modest sleep compensation during weekends has positive impact on glycemic control.