Women with sleeping problems may be more likely to develop diabetes

Difficulty in sleeping is associated with an increased risk of developing type 2 diabetes, a study published in Diabetologia has found.1

The US researchers found that the positive association was explained only partly by hypertension, body mass index, and depression. The association was particularly strong when combined with other sleep disorders such as frequent snoring or sleep apnoea.

Researchers analysed data from 133 353 women without diabetes, cardiovascular disease, or cancer at baseline from two large prospective cohorts. The two cohorts were the Nurses’ Health Study, which included women aged 30-55, and the Nurses’ Health Study II (NHSII), which included nurses aged 25-42.

At baseline 5.9% of women in the Nurses’ Health Study and 4.8% in NHSII reported having sleeping difficulty, defined as difficulty in falling or staying asleep “all of the time” or “most of the time.” The researchers found 6407 incident cases of type 2 diabetes during the 10 years of follow-up.

After adjustment for lifestyle factors at baseline, the risk of diabetes was 45% higher in women with sleeping difficulty than in those without (adjusted hazard ratio 1.45 (1.33 to 1.58)). After further adjustment for hypertension, depression, and body mass index based on updated repeated measurement, the hazard ratio changed to 1.22 (1.12 to 1.34).

Women who reported all of four sleep conditions—sleeping difficulty, frequent snoring, less than six hours’ sleep a night, and either sleep apnoea (in the Nurses’ Health Study) or working shifts (in NHSII)—had a more than four times higher likelihood of developing type 2 diabetes (4.17 (2.93 to 5.91)). Women who reported two conditions had around twice the risk of developing type 2 diabetes, and those with three conditions had around three times the risk.

Experimental studies have shown that inadequate sleep is associated with impaired glucose regulation in healthy young adults, the researchers wrote. Sleep disturbance has also been shown to adversely influence metabolism and has been linked to adverse outcomes including obesity, hypertension, and depression.

The researchers concluded, “Our findings highlight the importance of good sleeping patterns and having enough sleep for preventing type 2 diabetes . . . The findings provide evidence to clinical physicians and public health researchers for future diabetes prevention among a high risk population with multiple sleep disorders.”

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