Declining glucose metabolism across a week of sleep restriction

Aims: The incidence of diabetes has reached epidemic proportions and modern society is driven to sleep less. Sleep duration is associated with diabetes risk, and laboratory protocols have demonstrated increases in pre-diabetes indicators after sleep restriction (SR). The aim of this pilot study was to examine the daily effects of SR on glucose metabolism across a week. Methods: Twelve healthy males with a mean (± SD) age of 24.6 (± 3.1) yr participated in a laboratory-based study. They were allocated to a SR (n=6) or a control (n=6) condition. The protocol included a baseline day and seven experimental days. On the baseline night, all participants had 8 h time in bed (TIB). During experimental days, the SR condition had 4 h TIB/day and the control condition had 8 h TIB/day. Participants were woken at 08:00 h and completed a 2-h oral glucose tolerance test at 09:30 h each morning. This was conducted using a continuous glucose monitoring system to measure interstitial glucose concentrations. Results: Glucose metabolism was assessed from peak and 2-h glucose concentrations, and glucose disposal rate. Participants in each group did not differ at baseline. Mixed models analyses were conducted, with study day and condition as fixed factors. Results indicated no main effects of condition or study for any of the variables. An interaction between study day and condition was only found for peak glucose concentration F(7,65) = 2.32, p = .04. Peak concentration remained similar across days of the control condition; in the SR condition, it remained stable for four experimental days and then progressively increased. Discussion: Increasing peak glucose concentrations suggests rising insulin resistance or reduced insulin secretion, and is consistent with previous research regarding SR and declines in glucose metabolism. It appears that peak glucose levels escalate after four days of SR. This is of relevance for organisations developing shift work rosters that consider employee health. Refereed/Peer-reviewed