Relationships between Sleep Disordered Breathing and Glucose Metabolism in Polycystic Ovary Syndrome

Abstract

Women with polycystic ovary syndrome (PCOS) are insulin resistant and are at increased risk for sleep apnea, which, in turn, may contribute to insulin resistance. The objective of this study was to determine relationships between risk and severity of obstructive sleep apnea (OSA) and glucose metabolism in PCOS. This study included two cohorts of women with PCOS in a tertiary care hospital. Cohort 1 included 40 nondiabetics who completed the Epworth Sleepiness Scale, the Pittsburgh Sleep Quality, and the Berlin Questionnaire to assess risk of OSA; 32 of the 40 women had an oral glucose tolerance test. Cohort 2 included eight women who had a sleep study, glycosylated hemoglobin level, and an oral glucose tolerance test. In cohort 1, 62.5% of the women had poor sleep quality by Pittsburgh Sleep Quality Index, and 18 (45%) had chronic daytime sleepiness by Epworth Sleepiness Scale. Thirty of the 40 women had a high risk of OSA by Berlin Questionnaire. Women with high OSA risk had higher fasting insulin levels and homeostasis model assessment index compared with those with low OSA risk (168.2 +/- 17.3 vs. 97.2 +/- 6.4 pmol/liter, P = 0.011; 6.3 +/- 0.7 vs. 3.6 +/- 0.3 mg/dl x microU/ml, P = 0.014, respectively). Among women with normal glucose tolerance, insulin levels were significantly higher in those at high vs. low OSA risk, independently of body mass index. Women in cohort 2 had rapid eye movement (REM)-predominant OSA with lower sleep efficiency, longer sleep latency, and less REM sleep than controls. Glycosylated hemoglobin levels and the area under the glucose curve positively correlated with the apnea-hypopnea index (rP = 0.82, P = 0.013; rP = 0.96, P = 0.0008, respectively) and the number of oxygen desaturations in REM sleep (rP = 0.97, P = 0.0009; rP = 0.97, P = 0.005, respectively). PCOS is associated with poor sleep quality, daytime sleepiness, and increased risk for OSA. Insulin levels and measures of glucose tolerance in PCOS are strongly correlated with the risk and severity of OSA.