Inadequate sleep may impair insulin sensitivity in women independent of adiposity

The study included about 40 women who were randomly assigned to either restricted sleep or adequate sleep for six weeks. They were then crossed over to the other sleep condition. During sleep restriction, women slept an average of 6.2 hours per night versus 7-9 hours per night.

The researchers found a significant increase in fasting insulin levels and insulin resistance (IR) during sleep restriction, with the effect on insulin resistance particularly notable in postmenopausal women. This was independent of changes in adiposity and adiposity.

Insufficient sleep is associated with type 2 diabetes (T2D), yet there is no clarity on the causal impact of chronic insufficient sleep on glucose metabolism in women. Marie-Pierre St-Onge, Department of Medicine, Division of General Medicine, Columbia University Irving Medical Center, New York, NY, and colleagues investigated whether prolonged mild sleep restriction (SR), similar to real-world short sleep, impairs women's glucose metabolism.

The randomized, crossover study included about 40 women (aged 20–75 years) without cardiometabolic diseases and with actigraphy-confirmed habitual total sleep time (TST) of 7–9 h/night. There were two 6-week phases: maintenance of adequate sleep (AS) and 1.5 h/night SR.

Outcomes included insulin and plasma glucose levels, HOMA-IR values based on fasting blood samples, a total area under the curve for insulin and glucose, the disposition index from an oral glucose tolerance test, and the Matsuda index.

The study led to the following findings:

• The sample included 38 women (n = 11 postmenopausal women). Values were reported with ±SEM.
• Linear models adjusted for baseline outcome values demonstrated a reduction in total sleep time by 1.34 ± 0.04 h/night with sleep restriction versus adequate sleep.
• Fasting insulin (β = 6.8 ± 2.8 pmol/L) and HOMA-IR (β = 0.30 ± 0.12) values were increased with SR versus AS, with effects on HOMA-IR more pronounced in postmenopausal women compared with premenopausal women (β = 0.45 ± 0.25 versus β = 0.27 ± 0.13, respectively).
• Change in adiposity did not mediate the effects of SR on glucose metabolism or change results in the full sample when included as a covariate.

"Curtailing sleep duration to 6.2 h per night, implying the median sleep duration of US adults with short sleep, for six weeks impairs insulin sensitivity, irrespective of adiposity," the researchers wrote.

"Findings underscore insufficient sleep as a modifiable risk factor for IR in women to be targeted in diabetes prevention efforts," they concluded.

Reference:

Faris M. Zuraikat, Blandine Laferrère, Bin Cheng, Samantha E. Scaccia, Zuoqiao Cui, Brooke Aggarwal, Sanja Jelic, Marie-Pierre St-Onge; Chronic Insufficient Sleep in Women Impairs Insulin Sensitivity Independent of Adiposity Changes: Results of a Randomized Trial. Diabetes Care 2023; dc231156. https://doi.org/10.2337/dc23-1156