SAN FRANCISCO — A high risk for sleep apnea was common in women with polycystic ovary syndrome and was linked to high fasting insulin levels, Dr. Esra Tasali reported at a conference sponsored by the American Diabetes Association.
Women with PCOSand normal glucose tolerance who were at high risk for sleep apnea and were given oral glucose showed insulin levels that were twice those of women with lower risk for sleep apnea.
This finding suggests that sleep apnea might worsen the metabolic consequences of insulin resistance, accelerating the conversion from normal to impaired glucose tolerance, Dr. Tasali said.
Although the study does not establish causation, Dr. Tasali recommended that women with PCOS be systematically evaluated for sleep apnea, because its treatment might improve glucose metabolism.
A high risk for sleep apnea was observed in 30 of 40 women with PCOS, and 92% of the women had sleep problems, according to Dr. Tasali and her colleagues at the University of Chicago (J. Clin. Endocrinol. Metab. 2006;91:36–42).
Of the 40 women, 32 had previously been given an oral glucose tolerance test. Glucose tolerance was normal in 19 women. In 22 women at high sleep apnea risk, average fasting insulin levels were significantly higher (168 pmol/L) than they were in the 10 women at low apnea risk (97 pmol/L).
Among the 13 women with impaired glucose tolerance, glucose and insulin levels did not differ depending on the level of apnea risk.
Another cohort of eight women with PCOS underwent overnight polysomnography for symptoms suggestive of obstructive sleep apnea. Mean sleep efficiency was 80% in the women with PCOS, compared with 92% in a control group of age-matched, nonobese women. The women with PCOS also had significantly longer mean sleep latency (41 minutes vs. 10 minutes), and significantly shorter total sleep time (323 minutes vs. 442 minutes, a difference of almost 2 hours).
“Sleep apnea might be an intrinsic component of the metabolic disturbances that appear with polycystic ovary syn- drome,” said Dr. Tasali.
Furthermore, severity of sleep apnea as measured by the apnea-hypopnea index, and the degree of oxygen desaturations during rapid-eye-movement sleep, accounted for more than 90% of the variability in measures of glucose tolerance including hemoglobin A1c levels.
Together, these findings could mean that both glucose tolerance and sleep apnea are strongly influenced by a common mechanism in women with PCOS.
Dr. Tasali disclosed no conflicts of interest related to her presentation.