Associations among sleep disturbances, nocturnal sleep duration, daytime napping, and incident prediabetes and type 2 diabetes: the Heinz Nixdorf Recall Study

Objective: Poor sleep quality as well as short and long sleep duration has been linked to type 2 diabetes. In addition to confirmational analyses, we examined the impact of daytime napping on incident diabetes, and we assessed associations between sleep characteristics and incident prediabetes. Methods: In a subgroup of the Heinz Nixdorf Recall Study, a population-based cohort study in Germany (N = 2962; age 45-75 years, without history of cancer, stroke, or cardiovascular diseases), diabetes at baseline and at 5-year follow-up was assessed by self-report and measurement of serum glucose levels. Prediabetes was defined as impaired fasting glucose (6.1-6.9 mmol/L). A sleep questionnaire was used to assess difficulties falling asleep, difficulties maintaining sleep, early morning arousal, and duration of nocturnal and daytime sleep. Results: In adjusted regression models, short (<= 5 hours) and long (>= 7.5 hours) sleepers were at greater risk for diabetes (relative risk [RR] = 1.56, 95% confidence interval [CI] = 1.02-2.39, and 1.40, 95% CI = 1.01-1.96, respectively [reference: 7 hours]). Moreover, the prevalence of any regular sleep disorder was associated with incident diabetes (RR = 1.30, 95% CI = 1.01-1.68), and with incident prediabetes (RR = 1.31, 95% CI = 1.00-1.72). Regular daytime nappers had no increased risk of incident diabetes (RR = 1.00, 95% CI = 0.70-1.41). Conclusion: This study shows that people with regular sleep disorders, people with short and long sleep duration, but not regular daytime nappers are at increased risk of diabetes. Furthermore, regular sleep disorders are associated with an increased risk of prediabetes. (C) 2016 Elsevier B.V. All rights reserved.