Longer habitual afternoon napping is associated with a higher risk for impaired fasting plasma glucose and diabetes mellitus in older adults: results from the Dongfeng–Tongji cohort of retired workers

ObjectivesAfternoon napping is a common habit in China. We used data obtained from the Dongfeng–Tongji cohort to examine if duration of habitual afternoon napping was associated with risks for impaired fasting plasma glucose (IFG) and diabetes mellitus (DM) in a Chinese elderly population.MethodsA total of 27,009 participants underwent a physical examination, laboratory tests, and face-to-face interview. They were categorized into four groups according to nap duration (no napping, <30, 30 to <60, 60 to <90, and ⩾90 min). Logistic regression models were used to examine the odds ratios (ORs) of napping duration with IFG and DM.ResultsOf the participants, 18,515 (68.6%) reported regularly taking afternoon naps. Those with longer nap duration had considerably higher prevalence of IFG and DM. Napping duration was associated in a dose-dependent manner with IFG and DM (P < .001). After adjusting for possible confounders, longer nap duration (>60 min; all P < .05) was still significantly associated with increased risk for IFG, and longer nap duration (>30 min) was associated with increased risk for DM; however, this finding was not significant in the group with a nap duration of 60–90 min.ConclusionsLonger habitual afternoon napping was associated with a moderate increase for DM risk, independent of several covariates. This finding suggests that longer nap duration may represent a novel risk factor for DM and higher blood glucose levels.