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Variability in Sleep Duration Associated With Risk of Developing Type 2 Diabetes

Nov 20, 2015

Study focuses on older women who sleep 6 hours or less or increase sleep duration by 2 hours or more over several years.

There is minimal research conducted to examine the relationship between sleep and type 2 diabetes. Specifically, previous research lacks data on baseline sleep duration; long-term changes in sleep duration and concomitant changes in diet, physical activity, weight and subsequent diabetes. Therefore, researcher Elizabeth M. Cespedes, SM, from the Harvard School of Public Health, and colleagues conducted a cohort study to identify these parameters. The cohort study included 59,031 women between ages of 55 and 83 years without diabetes. These subjects were participating in the Nurses’ Health Study in 2000. Investigators of the study identified the difference between subjects’ who reported 24-hour sleep duration in 1986 and 2000. On the other hand, diet, physical activity and other covariates were updated every 2-4 years. Subjects responded about their diabetes diagnosis through questionnaires.


Researchers found that through 2012, there were 3,513 documented incident cases of diabetes; 49% of women reported sleeping 7 to 8 hours per night in both 1986 and 2000. On the other hand, 15% of subjects consistently reported sleeping less than 6 hours, and 2% reported sleeping more than 9 hours. Furthermore, 5% of subjects reported decreases in sleep time of 2 hours or more during the 14-year study period; 7% reported sleep increases of 2 hours or more.

Authors believe that both increases and decreases in sleep duration are associated with greater diabetes risk; however, this risk did not persist after adjustment for decreases in sleep.

Practice Pearls:

  • Chronic short sleep duration is associated with higher risk for diabetes.
  • Adverse associations are linked between sleep duration, diet quality and physical activity. However, diet and physical activity does not mediate the association between increased sleep duration and diabetes.
  • It is not evident to conclude that short or long sleepers who achieve normative sleep durations will experience benefits for metabolic health.

Cespedes, Elizabeth M., et al. “Long-term changes in sleep duration, energy balance and risk of type 2 diabetes.” Diabetologia (November 2, 2015): 1-9.