Women with sleeping problems have greater risk of type 2 diabetes, Harvard study reports

Women who have problems sleeping could have an increased risk of developing type 2 diabetes, according to a new Harvard study.
Scientists from the Harvard T H Chan School of Public Health, Bosto, evaluated data from the Nurses’ Health Study (NHS) I and II, which began in 1976 and 1989 respectively.
They analysed 133,353 women without diabetes, cardiovascular disease and cancer by the year 2000. The women were then questioned about their sleeping habits; all of the nurses remained in the NHS for up to 10 additional years.
During that 10-year period, 6,407 women self-reported a diagnosis of type 2 diabetes. 5.8 per cent of NHS I women and 4.8 per cent of NHS II women also reported having problems either falling asleep or staying asleep all or most of the time.
Those who reported having frequent trouble sleeping were 45 per cent more likely to develop type 2 diabetes that than those without sleeping problems.
This risk was further raised among women who reported having two or more sleeping disorders, such as sleep apnea and sleeping fewer than six hours, while women who had four different sleeping problems had a four-fold increased risk of type 2 diabetes.
These findings also accounted for variables such as socioeconomic status, physical activity and a family history of diabetes. When BMI, hypertension and depression were considered, there remained a 22 per cent risk of type 2 diabetes that was attributable to problems sleeping.
“Our findings highlight the importance of sleep disturbance in the development and prevention of type 2 diabetes,” the authors wrote.
They also noted their study is the first “to examine and quantify the mediation effects of chronic conditions on the association between sleeping difficulty and type 2 diabetes [and] examine the joint effects and test the interactions between sleeping difficulty and other sleep-related conditions on the risk of type 2 diabetes.”
However, the researchers were unable to explain how exactly poor sleep contributes to the development of type 2 diabetes, and further studies are warranted. Furthermore, this study did not examine any relationship between sleep loss and an increased risk of type 2 diabetes in men.
They concluded: “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 findings are published in the online journal Diabetologia.