Duration and Poor Quality of Sleep Associated with Greater Risk for Diabetes

Fewer than six hours or more than 10 hours of sleep, and poor quality of sleep are associated with a greater risk for diabetes, according to research presented at ENDO 2023.

Previous studies have looked at poor sleep quantity and quality, and its impact on the risk for diabetes or obesity. However, this study sought to explore the longitudinal effects.

“Most previous studies did not examine changes in various glycometabolic parameters, like over 14 years. The pattern of changes in various glycemic parameters may provide clues to the mechanism underlying the association between sleep duration and incident diabetes mellitus,” says first author Wonjin Kim, MD, PhD, of CHA Gangnam Medical Center and associate professor at CHA University School of Medicine in Seoul, South Korea.

For this study, the researchers collected data from 8,816 of 10,030 healthy participants of the ongoing Korean Genome and Epidemiology Study (KoGES)-Ansung and Ansan Cohort Study. They identified diabetes cases and sleep duration and quality. Sleep duration was categorized into four groups: less than six hours, six to seven hours, eight to nine hours, or nice hours per day. Sleep quality was measured among those with a sleep duration of less than 10 hours per day.

During the 14-year follow-up period, 18% (1630/8816) were diagnosed with diabetes. The researchers observed a U-shaped relationship between sleep duration and incident diabetes, with the greatest risk when sleep duration was ≥10 hours per day. During the study, this group also showed decreased insulin glycogenic index, which is a marker of insulin secretory function.

The risk for incident diabetes increased among study participants who slept <10 hours per day when their Epworth Sleepiness Scale (ESS) – which measures how likely a person is to fall asleep in situations like watching TV or being a passenger in a car in contrast to how tired that person is — score was greater than 10. (A score of 10 or greater may mean a need for more sleep or an improvement in sleep quality.)

“We found that the association between sleep duration and incident DM was U-shaped; both short (≤5 h) and long (≥10 h) sleep duration were associated with an increased risk for the occurrence of incident [type 2 diabetes mellitus (DM)],” the authors conclude. “When sleep duration was 10 h or longer per day, there was a tendency to develop DM due to decreased insulin secretory function. Even if the sleep duration is less than 10 h, the likelihood of developing diabetes is greater when the quality of sleep decreases.”