Assessment of sex differences in associations between sleep duration and lipid/glucose metabolism in urban Japan: a cross-sectional study.

Inadequate sleep durations (short or long) are related to worsening of lipid/glucose metabolism, leading to atherosclerotic cardiovascular diseases (ASCVD). Few data exist on sex differences in this relationship that, to date, has been scarcely reported. This cross-sectional study included 6678 men and 4700 women at the Health Planning Center of Nihon University Hospital, located in the center of Tokyo, between September 2015 and October 2016. The prevalence of diabetes and dyslipidemia in the participants was 3.3% and 6.5%, respectively. Sleep duration was divided into five categories: < 5 h, 5-6 h, 6-7 h, 7-8 h, and ≥ 8 h. We examined the odds ratio (OR) and 95% confidence interval (CI) of lipid/glucose metabolism-related markers for the reference value defined in each guideline with 6-7 h as the reference of comparison. In men, a sleep duration of < 5 h was associated with ORs of 1.32 and 1.33 (95% CI, 1.01-1.73 and 1.02-1.74) for LDL-C level ≥ 120 mg/dL and non-HDL-C level of ≥ 150 mg/dL (defined as "borderline hyper" by the Japan Atherosclerosis Society Guidelines for Prevention of ASCVD 2017), respectively. Moreover, a sleep duration of < 5 h was associated with an OR of 1.77 (1.33-2.35) for fasting blood glucose of ≥ 100 mg/dL (defined as "high" by a specialized lifestyle checkup program in Japan). In women, sleep duration of < 5 h was associated with an OR of 1.70 (1.24-2.33) for HbA1c level of ≥ 5.6% (defined as "high" by a specialized life style checkup program in Japan). However, there was no association between sleep duration and serum lipid profile. Inadequate short sleep duration was as a potential risk factor of adverse lipid and/or glucose metabolism in both sexes. However, there were sex differences in associations between sleep duration and lipid/glucose metabolism in urban Japan. To further reduce risks of ASCVD, it is of particular importance to emphasize adequate sleep duration in both sexes.Trial registration UMIN ( http://www.umin.ac.jp/ ) Study ID: UMIN000037643 retrospectively registered on August 9, 2019.