Sleep Issues Linked to Diabetes

Sleep issues significantly increase the risk of women developing type 2 diabetes mellitus (T2DM), according to the first study to examine the link between sleeping difficulty and other sleep-related conditions on the risk of T2DM.

The results suggest sleep habits may help identify patients who may benefit from diabetes-prevention programs.

“Our findings highlight the importance of sleep disturbance in the development and prevention of type 2 diabetes,” state the authors, led by Yanping Li, MD, PhD, from the Department of Nutrition, Harvard TH Chan School of Public Health in Boston, MA.

The researchers noted that this association was partially explained by associations with hypertension, body mass index (BMI), and depression symptoms, and was particularly strong when combined with other sleep disorders.

Sleeping difficulty has been associated with T2DM, but it is unclear whether the associations are independent of health behaviors, other cardiovascular risk factors, or other sleep disorders, the researchers state.

They analyzed data from 133,353 women who did not have diabetes, cardiovascular disease, or cancer at baseline who were participating in the Nurses’ Health Study (NHS) and the follow-up NHSII. They noted which women had any of four sleep conditions: sleeping difficulty, frequent snoring, sleep duration of 6 hours or less, and sleep apnea in NHS or rotating shift work in the NHSII studies. They defined sleep difficulty as having difficulty falling or staying asleep all or most of the time.

Among the participants, 6,407 incident cases of T2DM were documented during up to 10 years of follow-up. After adjustment for lifestyle factors at baseline, comparing women with and without sleeping difficulty, a multivariate analysis found a 45% higher risk for T2DM.

This was changed to a 22% higher risk after further adjustment for hypertension, depression, and BMI based on updated repeated measurements.

Those women who experienced two sleeping conditions had about twice the risk of developing T2DM, and those with three conditions had about three times the risk.

“Women who reported all four sleep conditions had more than a four-fold increased likelihood of type 2 diabetes,” they state.

Shift work, in particular, seemed to have a significant effect. The multivariate-adjusted hazard ratios of shift work only was 1.27, for sleeping difficulty only was 1.40, and for both conditions combined was 2.30, as compared with women without sleeping difficulty who did no shift work. So it appears that women with sleeping difficulty who do shift work face a double whammy that significantly increases their risk of T2DM.

As for the mechanism of the association, the researchers suggest that sleeping difficulty may influence metabolism and produce obesity by disturbing circadian rhythms and other physiological function. This may indirectly increase the risk of diabetes by altering appetite-regulating hormones.

In addition, sleep disturbance may increase blood pressure and sympathetic nervous system activity, which may influence insulin sensitivity.

The researchers conclude that “the findings provide evidence to clinical physicians and public-health researchers for future diabetes prevention among a high-risk population with multiple sleep disorders.”

Reference: Li Y, et al. Association between sleeping difficulty and type 2 diabetes in women. Diabetologia. 2016 Jan 28. [Epub ahead of print]