Numerous investigations have observed associations between sleep quality and morbidity and mortality. A recent Japanese study published in PLoS ONE aimed to understand the link between glycemic control in diabetes and sleep quality.
Sleep disorders are very common among diabetic patients. Poor sleep quality has been associated with an increased risk of the onset of diabetes. Sleep disorders also have a significant impact on glycemic control in type 2 diabetic patients. Researchers at the Yokohama City University Medical Centre in Japan conducted a study among over 3,000 Japanese diabetic patients to survey sleep quality and to assess the link between diabetes and sleep quality. The results of this study were published in the journal PLoS ONE.
Is Diabetes Control Associated with Sleep Quality?
Sleep quality was assessed using a validated self-questionnaire called the Pittsburgh Sleep Quality Index (PSQI), which measures seven aspects of sleep quality including sleep latency, sleep duration, and the use of sleeping pills. Almost half of the patients surveyed (47.6%) had a PSQI score of six or higher, indicating poor sleep quality. The highest score among the different components of the questionnaire was for sleep duration, followed by subjective sleep quality, and then sleep latency. The average sleep duration score of all of the diabetic patients in this study was significantly lower than that of the general population in Kanagawa Prefecture. These findings confirm results from prior studies conducted among Japanese diabetic patients.
Higher Blood Sugar Associated with Poor Sleep Quality
Once patients were assigned to different groups based on their glycated hemoglobin (HbA1c) levels, which is a measure of diabetic control, the researchers noted that patients in the top (i.e. worst controlled) quartile had the highest PSQI scores. Also, the scores in the sleep duration, subjective sleep quality, and sleep latency components of the questionnaire were significantly higher in the top quartile group. All of these findings remained consistent when the researchers adjusted the results for confounding factors such as age, gender, body mass index, smoking status, and diabetic neuropathy (nerve damage resulting in tingling, numbness, and/or pain in the extremities).
One theory explaining the observed lack of glycemic control in diabetic patients with poor sleep quality is an increased level of cortisol caused by reduced sleep duration. High cortisol levels can lead to progressive insulin resistance. Further investigations are necessary to confirm the findings of this study and to identify the underlying mechanisms involved.
This study observed the link between diabetes and sleep quality. Japanese diabetic patients showed shorter sleep durations that the general Japanese population. Patients with worse glycemic control had significantly poorer sleep quality than diabetic patients with more controlled blood sugar levels. Among proper nutrition and physical activity, sleep quality may be another factor involved in diabetes management.
Written by Jessica Caporuscio, PharmD
(1) Sakamoto R, Yamakawa T, Takahashi K, et al. Association of usual sleep quality and glycemic control in type 2 diabetes in Japanese: A cross sectional study. Sleep and Food Registry in Kanagawa (SOREKA). PLoS One. 2018.
(2) Buysse DJ, Reynolds CF 3rd, Monk TH, et al. The Pittsburgh Sleep Quality Index: a new instrument for psychiatric practice and research. Psychiatry Res. 1989.