Objective: Evidence suggests that short and long sleep durations are associated with a higher risk of type 2 diabetes. Using successive data waves spanning >20 years, we examined whether a change in sleep duration is associated with incident diabetes.
Research design and methods: Sleep duration was reported at the beginning and end of four 5-year cycles: 1985-1988 to 1991-1994 (n = 5,613), 1991-1994 to 1997-1999 (n = 4,193), 1997-1999 to 2002-2004 (n = 3,840), and 2002-2004 to 2007-2009 (n = 4,195). At each cycle, change in sleep duration was calculated for participants without diabetes. Incident diabetes at the end of the subsequent 5-year period was defined using 1) fasting glucose, 2) 75-g oral glucose tolerance test, and 3) glycated hemoglobin, in conjunction with diabetes medication and self-reported doctor diagnosis.
Results: Compared with the reference group of persistent 7-h sleepers, an increase of ≥2 h sleep per night was associated with a higher risk of incident diabetes (odds ratio 1.65 [95% CI 1.15, 2.37]) in analyses adjusted for age, sex, employment grade, and ethnic group. This association was partially attenuated by adjustment for BMI and change in weight (1.50 [1.04, 2.16]). An increased risk of incident diabetes was also seen in persistent short sleepers (average ≤5.5 h/night; 1.35 [1.04, 1.76]), but this evidence weakened on adjustment for BMI and change in weight (1.25 [0.96, 1.63]).
Conclusions: This study suggests that individuals whose sleep duration increases are at an increased risk of type 2 diabetes. Greater weight and weight gain in this group partly explain the association.
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