Observational Study
Copyright ©The Author(s) 2017. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Diabetes. Aug 15, 2017; 8(8): 397-406
Published online Aug 15, 2017. doi: 10.4239/wjd.v8.i8.397
Age-dependent changes in the association between sleep duration and impaired glucose metabolism
Kei Nakajima, Kaname Suwa, Kenji Toyama
Kei Nakajima, Kenji Toyama, School of Nutrition and Dietetics, Faculty of Health and Social Services, Kanagawa University of Human Services, Yokosuka, Kanagawa 238-8522, Japan
Kei Nakajima, Department of Endocrinology and Diabetes, Saitama Medical Center, Saitama Medical University, Saitama 350-8550, Japan
Kaname Suwa, Saitama Health Promotion Corporation, Yoshimimachi, Hikigun, Saitama 355-0133, Japan
Author contributions: Nakajima K designed the overall study and analyzed the data; Suwa K identified eligible subjects from the database at Saitama Health Promotion Corporation and confirmed validation of the measurements and methods; Toyama K prepared the manuscript, including editing and discussion; Nakajima K wrote the manuscript and is the guarantor of the manuscript; all authors read and approved the final manuscript.
Institutional review board statement: The study was reviewed and approved by the Ethics Committee of Kanagawa University of Human Services Institutional Review Board.
Informed consent statement: All subjects provided informed written consent.
Conflict-of-interest statement: The authors have no conflict of interest to declare.
Data sharing statement: No additional data are available.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Kei Nakajima, MD, PhD, School of Nutrition and Dietetics, Faculty of Health and Social Services, Kanagawa University of Human Services, 1-10-1 Heisei-cho, Yokosuka, Kanagawa 238-8522, Japan. nakajima-rsh@kuhs.ac.jp
Telephone: +81-46-8282660 Fax: +81-46-8282661
Received: October 20, 2016
Peer-review started: October 31, 2016
First decision: January 14, 2017
Revised: March 3, 2017
Accepted: March 16, 2017
Article in press: March 17, 2017
Published online: August 15, 2017
Processing time: 287 Days and 10.2 Hours
Abstract
AIM

To investigate whether the association between sleep duration and impaired glucose metabolism varies among younger and older populations.

METHODS

We reviewed data of self-reported habitual sleep duration per night, HbA1c levels, and clinically relevant factors in a cross-sectional checkup database of 75472 Japanese from the general population aged 20-79 years (51695 men and 23777 women). Associations of prediabetes (HbA1c ≥ 5.7% and/or diabetic pharmacotherapy) or diabetes (HbA1c ≥ 6.5% and/or diabetic pharmacotherapy) with short and long sleep durations compared with a reference sleep duration (7 h) were investigated by multivariate logistic regression analysis. We controlled for potential relevant confounders, including age, sex, and work duration per day according to younger and older subjects.

RESULTS

As age advanced, sleep duration became longer and this increase in the 40s and 50s was two times greater in men than in women. This finding was accompanied by a deterioration in HbA1c levels. In subjects aged younger than 40 years (n = 32929), HbA1c levels were inversely and linearly correlated with sleep duration in both sexes. However, in subjects aged 40 years or older (n = 42543), HbA1c levels showed a non-linear relationship against sleep duration with a nadir at 7 h. Multivariate logistic regression analysis showed that in younger subjects, short durations of sleep (≤ 5 h and 6 h) were positively associated with prediabetes (both P < 0.001), but a long duration of sleep (≥ 8 h) was inversely associated with prediabetes (P < 0.001). These associations remained significant after adjustment for relevant confounders, including age, sex, and work duration per day (ORs = 1.20, 95%CI: 1.05-1.37, P < 0.001; ORs = 1.12, 95%CI: 1.02-1.24, P < 0.05; and ORs = 0.84, 95%CI: 0.72-0.99, P < 0.05, respectively). In contrast, in older subjects, besides an association of prediabetes with a short duration of sleep (≤ 5 h) (ORs = 1.12, 95%CI: 1.03-1.21, P < 0.01), diabetes was significantly associated with a long duration of sleep (≥ 8 h) (ORs = 1.11, 95%CI: 1.02-1.25, P < 0.05).

CONCLUSION

A short sleep duration may be associated with prediabetes throughout life. However, the association between a long sleep duration and glucose metabolism can change with aging.

Keywords: Sleep; Prediabetes; Diabetes; HbA1c; Aging

Core tip: Short and long durations of sleep have been putatively associated with type 2 diabetes. However, whether age affects these associations is unknown, although sleep duration and glucose homeostasis can change with advancing age. Our study demonstrated that a short sleep duration may be associated with prediabetes throughout the lifespan, whereas a long duration of sleep may be inversely associated with prediabetes in younger subjects. Additionally, a long sleep duration was associated with diabetes in older subjects. Therefore, aging may substantially affect the association between a long sleep duration and glucose homeostasis.