Diabetes Q&A

Could Increased Sleep Duration Raise the Risk of Diabetes in Women?

Gradually increasing sleep times over several years is associated with a modest increase in the risk of type 2 diabetes in middle-aged and older women, according to a recent study.

Previous studies predominantly used singular measurements of sleep when examining the relationship between sleep habits and diabetes risk. Therefore, existing studies cannot be used to examine the effects of changes in sleep times.
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To further examine this subject, researchers followed 59,031 women between the ages of 55 and 83 years old. The women were all participants in the nurses’ Health Study and were all without diabetes in 2000. Researchers used the difference between self-reported 24-hour total sleep time measured in 1986 and 2000 to calculate long-term sleep duration changes.

Researchers also recorded data on participants’ diet, physical activity, and other covariates every 2-4 years.

Forty-nine percent of the women reported consistently sleeping between 7 and 8 hours a night between 1986 and 2000, 15% consistently of women slept 6 hours or less each night, and 2% consistently slept 9 hours or more a night, while 5% and 7% reported dramatic decreases and increases, respectively, of 2 or more hours a night.

Overall, 3513 cases of diabetes were reported through 2012. After adjusting for covariates, researchers reported the following hazard ratios:

  • ≤-2 hours per day: 1.09 (95% CI 0.93-1.28)
  • >-2 to <0 hours per day: 1.10 (95% CI 1.001-1.12)
  • >0 to <2 hours per day: 1.09 (95% CI 1.00-1.18)
  • ≥2 hours per day: 1.30 (95% CI 1.14-1.46)

Adjustment for diet and physical activity did not significantly alter these results, and increases in sleep duration remained adversely associated with diabetes after adjustment for changes in covariates between 1986 and 2000.

“Increases in sleep duration among middle-aged and older women were modestly associated with risk of diabetes; changes in diet, physical activity and body mass index did not explain associations,” they concluded.

—Michael Potts

Reference:
Cespedes EM, Bhupathiraju SN, Li Y, et al. Long-term changes in sleep duration, energy balance and risk of type 2 diabetes. Diabetologia. 2015 November [epub ahead or print]. DOI 10.1007/s00125-015-3775-5.