The relationship between sleep and glucagon-like peptide 1 in patients with abnormal glucose tolerance.

Glucagon-like peptide 1 plays a role in glucose regulation. Sleep disturbances (obstructive sleep apnea, insufficient or poor sleep quality) have been shown to adversely affect glucose metabolism. This study aimed to explore the relationship between sleep and glucagon-like peptide 1 regulation in patients with abnormal glucose tolerance. Seventy-one adults with haemoglobin A1c levels between 5.7% and < 6.5% and no history of diabetes participated. Habitual sleep duration and efficiency were obtained from 7-day actigraphy recordings. Obstructive sleep apnea was assessed using an overnight home monitor. Glucagon-like peptide 1 levels were measured during a 75-g glucose tolerance. The area under the curve of glucagon-like peptide 1 was calculated. The mean age (SD) was 55.1 (8.3) years and median (interquartile range) haemoglobin A1c was 5.97% (5.86, 6.23). There was no relationship between sleep duration or efficiency and fasting or area under the curve glucagon-like peptide 1. Glucagon-like peptide 1 levels did not differ among those sleeping ≤ 5.75, > 5.75-< 6.5 or ≥ 6.5 h per night. Increasing apnea-hypopnea index, an indicator of obstructive sleep apnea severity, correlated with lower area under the curve glucagon-like peptide 1 (B -0.242, P = 0.045), but not with fasting glucagon-like peptide 1 (B -0.213, P = 0.079). After adjusting for sex, haemoglobin A1c and body mass index, increasing apnea-hypopnea index was negatively associated with having area under the curve glucagon-like peptide 1 in the highest quartile (odds ratio 0.581, P = 0.028, 95% CI 0.359, 0.942). This study demonstrated that increasing obstructive sleep apnea severity was associated with lower glucagon-like peptide 1 response to glucose challenge. This could possibly be an additional mechanism by which obstructive sleep apnea affects glucose metabolism. Whether raising glucagon-like peptide 1 levels in patients with abnormal glucose tolerance with more severe obstructive sleep apnea will be beneficial should be explored.