Sleep apnea with polycystic ovary syndrome raises risk of prediabetes
Women with polycystic ovary syndrome (PCOS) who also have obstructive sleep apnea have at least three times the risk of having prediabetes compared with women who do not have PCOS, according to a new study. The results will be presented Tuesday at The Endocrine Society’s 94th Annual Meeting in Houston.
“In the last few years, sleep apnea has been found to be a frequent comorbidity [coexisting condition] with PCOS, and our study shows that women who have both conditions are at greatest risk of metabolic disturbances such as prediabetes,” said the study’s senior author, David Ehrmann, MD, a University of Chicago professor of medicine and director of the University of Chicago Center for PCOS.
“Patients who have one or both of these conditions should be screened early for Type 2 diabetes and should be monitored regularly,” Ehrmann said.
He and his colleagues studied 171 obese women: 121 with PCOS, a common female hormonal disorder that affects 5 to 10 percent of women of childbearing age, and 50 without PCOS. All study subjects had an oral glucose tolerance test, which measures the blood sugar level before and for two hours after the patient drinks a sugary solution. If the blood glucose level at two hours is less than 140 mg/dL, it is considered normal. Levels above 200 mg/dL indicate Type 2 diabetes, and levels between 140 and 200 mg/dL are diagnostic of impaired glucose tolerance, also called prediabetes. Prediabetes often progresses to Type 2 diabetes.
Additionally, all women had an overnight sleep study, called a polysomnogram, to look for obstructive sleep apnea, in which breathing stops repeatedly during sleep. Mild sleep apnea is defined as having between 5 and 15 such episodes per hour of sleep; moderate sleep apnea exists when 15 to 30 episodes occur per hour and severe sleep apnea is present when more than 30 such episodes occur per hour. There appears to be a strong relationship between sleep apnea severity and diabetes risk, Ehrmann said.
In women with PCOS, sleep apnea was more prevalent than in the control subjects without PCOS (48 percent versus 36 percent, respectively), and when present, it also was more severe, the authors reported. Similarly, PCOS-affected women were more likely to have prediabetes - 44 percent versus 22 percent of controls.
What is polycystic ovary syndrome?
Polycystic (literally, many cysts) ovary syndrome (PCOS or PCO) is a complex condition that affects the ovaries (the organs in a woman’s body that produce eggs).
It’s complex because there are some very typical appearances in the ovaries that give the condition its name. But these are not always present and do not have to be present.
In PCOS, the ovaries are generally bigger than average. The outer surface of the ovary has an abnormally large number of small follicles (the sac of fluid that grows around the egg under the influence of stimulating hormones from the brain).
There are also characteristic changes in the appearance of the ovaries on an ultrasound scan.
The ovaries are polycystic, with many small follicles scattered under the surface of the ovary (usually more than 10 or 15 in each ovary) and almost none in the middle of the ovary. These follicles are all small and immature, and generally do not exceed 10mm in size and rarely, if ever, grow to maturity and ovulate.
In PCOS, these follicles remain immature, never growing to full development or ovulating to produce an egg capable of being fertilised. For the woman, this means that she rarely ovulates (releases an egg) and so is less fertile. In addition, she doesn’t have regular periods and may go for many weeks without a period. Other features of the condition are excess weight and body hair.
The condition is relatively common among infertile women. If affects up to 10 per cent of all women between the ages of 15 and 50 and is particularly common among women with ovulation problems (an incidence of about 75 per cent).
The investigators found that the greater the severity of obstructive sleep apnea in women with PCOS, the higher their two-hour blood sugar values were on the glucose tolerance test.
The research team also found that the lower the levels of the female hormone progesterone, the higher the blood sugar values. Progesterone is typically low in women with PCOS, and Ehrmann said insufficient progesterone may contribute to obstructive sleep apnea. Notably, high testosterone levels were not predictive of sleep apnea or abnormal glucose tolerance, he said.
Polycystic Ovarian Syndrome (PCOS), also known as Polycystic Ovarian Disease, is often caused by a hormonal imbalance brought on by Insulin Resistance-related obesity. It’s a disorder that affects an estimated 5 - 10 percent of women, and is a leading cause of infertility.
Symptoms of PCOS can vary widely from woman to woman and can include: irregular or completely absent periods, ovarian cysts, Hirsutism (excessive facial or body hair), Alopecia (male pattern hair loss), obesity, acne, skin tags, Acanthosis Nigricans (brown skin patches), High cholesterol levels, exhaustion or lack of mental alertness, decreased sex drive, excess male hormones, and infertility. Other symptoms can include sleep apnea (breathing difficulties during sleeping), thyroid disorders and depression and anxiety.
Current studies link Polycystic Ovarian Syndrome and Insulin Resistance. A report released in the British Journal of Obstetrics and Gynecology in 2000 indicated that up to 40 percent of women with PCOS have either impaired glucose tolerance or Type 2 Diabetes by age 40. In addition, with Polycystic Ovarian Syndrome, high levels of insulin stimulate the ovaries to produce large amounts of testosterone (a male hormone), which can contribute to infertility by possibly preventing the ovaries from releasing an ovum each month. High testosterone levels can also cause excessive hair growth, male pattern baldness, and acne.
PCOS is one of the most common endocrine (or hormonal) disorders and is characterized by multiple abnormal cysts in the ovaries.
PCOS causes the ovaries to produce an excess of male hormones and is the most common cause of female infertility. It also can result in obesity, acne, thinning hair on the scalp and excessive facial and body hair.
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This study received funding from the National Institutes of Health Specialized Centers of Research on Sex Differences Research and the Blum-Kovler Foundation in Chicago.
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Aaron Lohr
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The Endocrine Society