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Sleep apnea may boost risk for impaired glucose tolerance in PCOS

NEW YORK (Reuters Health) – Women with polycystic ovary syndrome (PCOS) who also have obstructive sleep apnea may be at higher risk for impaired glucose intolerance and prediabetes, researchers said last week at the annual meeting of the Endocrine Society in Houston, Texas.

“In the last few years, sleep apnea has been found to be a frequent comorbidity with PCOS, and our study shows that women who have both conditions are at greatest risk of metabolic disturbances such as prediabetes,” said senior investigator Dr. David Ehrmann from the University of Chicago, in a statement.

In light of the finding, women with PCOS should be screened for sleep apnea with polysomnography, and also for prediabetes with an oral glucose tolerance test, Dr. Ehrmann told Reuters Health.

In the study, 117 women with polycystic ovary syndrome and 48 controls underwent both tests: overnight polysomnography and a two-hour 75g oral glucose tolerance test with blood sampling every 30 minutes.

The mean body mass index in both groups was nearly 40kg/m2.

More women with PCOS had sleep apnea (48% vs 36%, p=0.03; odds ratio 2.4). Their sleep apnea was also more severe, as measured by the Apnea-Hypopnea Index (median 4.6 vs. 2.1, p=0.000047).

And more women with PCOS had either diabetes or prediabetes, at 44% compared to 22% of the control group.

In logistic regression models, sleep apnea and its severity were risk factors for prediabetes, but only in the women with polycystic ovary syndrome (p<0.01). The result held up even after controlling for age, BMI, race and hormone levels (testosterone and progesterone).

Sleep apnea apparently increased the risk threefold after controlling for race and either sleep apnea (OR =3.4; p=0.01) or Apnea-Hypopnea Index (OR=2.9 p=0.02).

“Women with PCOS are predisposed to develop impaired glucose tolerance and they’re very insulin resistant,” Dr. Ehrmann said. “It’s only a subset of women, and sleep apnea is associated with impaired glucose tolerance and insulin resistance itself. So it’s kind of a third factor that contributes to glucose intolerance.”