Objective: We examined the joint effects of insomnia and objective short sleep duration, the combination of which is associated with higher morbidity, on diabetes risk.
Research design and methods: A total of 1,741 men and women randomly selected from Central Pennsylvania were studied in the sleep laboratory. Insomnia was defined by a complaint of insomnia with duration of >or=1 year, whereas poor sleep was defined as a complaint of difficulty falling asleep, staying asleep, or early final awakening. Polysomnographic sleep duration was classified into three categories: >or=6 h of sleep (top 50% of the sample); 5-6 h (approximately third quartile of the sample); and <or=5 h (approximately the bottom quartile of the sample). Diabetes was defined either based on a fasting blood glucose >126 mg/dl or use of medication. In the logistic regression model, we simultaneously adjusted for age, race, sex, BMI, smoking, alcohol use, depression, sleep-disordered breathing, and periodic limb movement.
Results: Chronic insomnia but not poor sleep was associated with a higher risk for diabetes. Compared with the normal sleeping and >or=6 h sleep duration group, the highest risk of diabetes was in individuals with insomnia and <or=5 h sleep duration group (odds ratio [95% CI] 2.95 [1.2-7.0]) and in insomniacs who slept 5-6 h (2.07 [0.68-6.4]).
Conclusions: Insomnia with short sleep duration is associated with increased odds of diabetes. Objective sleep duration may predict cardiometabolic morbidity of chronic insomnia, the medical impact of which has been underestimated.