Evidence suggests short or long sleep duration is associated with a higher risk of diabetes. Using a large longitudinal data set spanning 2 years, we examined whether a change in sleep duration is associated with diabetes.Current analysis included 56,588 participants who were free of diabetes during both 2006-2007 (exam1) and 2008-2009 (exam2). Sleep duration was categorized into 7 groups: ≤5.5 hours, 6.0 to 6.5 hours, 7.0 hours, 7.5 to 8.0 hours, ≥8.5 hours, decrease ≥2 hours, and increase ≥2 hours. Cox proportional hazards models were used to calculate hazard ratios (HRs) and their confidence intervals (CI) for diabetes, according to sleep duration.Compared to the reference group of persistent 7-h sleepers, participants who slept 7.5 to 8 hours per night (HR, 1.20; 95% CI, 1.02-1.40), ≥8.5 hours per night (HR, 1.37; 95% CI, 1.03-1.81) and an increase of ≥2 hours sleep per night (HR, 1.24; 95% CI, 1.05-1.48) were all associated with an increased risk of developing diabetes in analyses adjusted for age, sex, education level, income level, smoking status, drinking status, physical activity, BMI, snoring status, hypertension, hyperlipidemia, and family history of diabetes. The abovementioned associations of sleep duration and incident diabetes were only prominent among individuals aged <64 years.This study suggests that individuals whose sleep duration increases ≥2 hours per night are at an increased risk of diabetes.