Women With Sleep Trouble Have High Type 2 Diabetes Risk

Marcia Frellick

January 28, 2016

Women who have problems sleeping have an increased risk for type 2 diabetes that ranges from 47% higher for those who have one sleep disorder to four times the risk for four disorders combined, according to new data.

The results have implications for clinicians in that they emphasize the need for more discussions with patients about their sleeping habits to help identify those who may benefit greatly from diabetes-prevention programs, according to lead author Yanping Li, MD, PhD, with the Harvard TH Chan School of Public Health in Boston, Massachusetts.

"Patients and physicians don't take this seriously enough," she told Medscape Medical News.

Working Rotating Shifts Had Detrimental Effect

Dr Li and colleagues found the link between poor sleep and type 2 diabetes was partly explained by associations with hypertension, body mass index (BMI), and depression. Results were published online January 28 in Diabetologia.

The authors 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 NHSII.

They noted whether the women had reported any of the following: sleeping difficulty; frequent snoring; sleeping 6 hours or less; and sleep apnea in NHS or rotating shift work in NHSII. Sleeping difficulty is defined as having difficulty falling or staying asleep all or most of the time.

The researchers looked at which women developed type 2 diabetes over 10 years and found 6407 cases. After adjustment for lifestyle factors at baseline, comparing women with and without sleeping difficulty, the multivariate-adjusted hazard ratio (HR) for type 2 diabetes was 1.45. That changed to 1.22 after further adjustment for hypertension, depression, and BMI.

Those women who experienced two sleeping conditions had around twice the risk of developing type 2 diabetes, while for three conditions it was around three times the risk, and for four it was more than a fourfold increased likelihood of developing type 2 diabetes (HR, 4.17).

Because the cohorts involved nurses, this gave the researchers the opportunity to include an analysis of the effects of rotating shift work on both sleep habits and type 2 diabetes risk.

They observed a significant interaction between sleeping difficulty and rotating shift work on risk of type 2 diabetes (P for multiplicative interaction = .08; P for additive interaction = .04).

"The multivariate-adjusted HRs of shift work only, sleeping difficulty only, and with both conditions were 1.27, 1.40, and 2.30, respectively, as compared with women without sleeping difficulty [who had done no] shift work in NHSII," the authors write.

This implies that more diabetes cases would occur in women with sleeping difficulty who worked in rotating shifts than in women with just one of these two risk factors.

The interactions between sleeping difficulty and the other sleep conditions in the study were not significant.

Sleeping Disorders Common: What's the Link With Diabetes?

Sleeping difficulty affects 10% to 20% of the general United States population, the authors note, and that number is growing along with the growing prevalence of type 2 diabetes. They note that the number of outpatient visits attributed to sleeping difficulty increased from 4.9 million in 1999 to 5.5 million in 2010.

The study is the first to look at joint effects and interactions between sleeping difficulty and other sleep-related conditions on risk of type 2 diabetes, the researchers say.

While the exact mechanisms are not known, sleeping difficulty may influence metabolism and produce obesity by disturbing circadian rhythms and other physiological function, including alterations in appetite-regulating hormones, indirectly increasing the risk of diabetes, Dr Li and colleagues say.

And sleep disturbance is associated with hypertension by increasing blood pressure and sympathetic nervous system activity, which may influence insulin sensitivity.

Limitations include the fact that only women were studied and they were primarily white. Dr Li cautioned against generalizing the results to all women and to men.

Nevertheless, "the findings provide evidence to clinical physicians and public-health researchers for future diabetes prevention among a high-risk population with multiple sleep disorders," the researchers conclude.

The study was supported by grants from the National Institutes of Health. Dr Li has no relevant financial relationships. Disclosures for the coauthors are listed in the article.

Diabetologia. Published online January 28, 2016. Abstract

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