Intra-individual variability in sleep is related to glycaemic control in adults with type 2 diabetes

To examine whether there were significant differences in sleep during weekdays/weekends and whether the intra-individual variability in sleep was related to glycaemic control in patients with type 2 diabetes.

Correlational, longitudinal design.

Data were collected between February 2017-January 2018. In all, 56 adults with type 2 diabetes were included (60.7 years, 55.4% female). Sleep was measured using the Consensus Sleep Diary over 8 days. Intra-individual variability of sleep was calculated as the standard deviation of sleep variables. Standard deviations of sleep duration, sleep efficiency, sleep quality, and mid-sleep time were obtained. Glycaemic control was measured by haemoglobin A1C. Paired t test and multiple regression analysis were used.

Overall, there were no differences in sleep parameters between weekdays and weekends. Participants slept 20 min more over the weekends than during weekdays. The mid-sleep time during weekends was about 35 min later than during weekdays. Intra-individual variability of sleep duration and mid-sleep ranged from 27.6-167.4 min and 13-137 min, respectively. Controlling for covariates (e.g., distress, symptoms, and self-care), larger variability in sleep duration, and mid-sleep were significantly related to higher A1C levels.

Diabetes educators are recommended to include the assessment of intra-individual variability in sleep. Maintaining a regular sleep habit (e.g., sleep duration and sleep timing) should be highlighted during patient education.

Intra-individual variability in sleep is an alternative dimension for sleep assessment. This study examined whether intra-individual variability in sleep was related to glycaemic control in an older sample of type 2 diabetes patients using a sleep diary across 8 days. This sample had a similar sleep pattern during weekdays and weekends. Larger intra-individual variabilities in sleep duration and mid-sleep time were independently related to worse glycaemic control. Diabetes patients are recommended to maintain a regular sleep routine.