Learning Center

PCOS and Diabetes

Polycystic Ovary Syndrome Sister to Type 2

By John Nestler

Lately you’ve been missing periods, but you’re not pregnant. What’s going on? Is your diabetes involved?

Jane is a 31 year old woman who recently developed type 2 diabetes. When she went to an endocrinologist to learn more about her condition, she was surprised by some of the doctor’s questions. He asked her about her menstrual cycle and whether she had any excess hair growth.

As it turns out, Jane had been having only four or five menstrual periods a year since she started menstruating at age 14, and never had been able to become pregnant. And she always did have a problem with a little “moustache.” Although the questions and answers seemed to Jane to be irrelevant to her case, her doctor was able to clear things up for her by explaining the he suspected a condition called “polycystic ovarian syndrome” (PCOS), and that it might intimately linked to her diabetes.

Jane’s doctor prescribed metformin, which was effective in treating her diabetes and bringing her blood glucose back to normal. Jane began to menstruate on a regular monthly basis and noticed a decrease in the amount of facial hair growth. Several months later, while she was in good blood glucose control, she became pregnant.

What is PCOS?

PCOS is a condition in which a woman’s ova, or eggs, mature in the ovary, but are not released. This failure to ovulate results in a decreased frequency of menstrual periods (usually eight or less per year) and causes cysts to develop in the ovaries.

Another feature of PCOS is elevated blood levels of male sex hormones such as testosterone, which can promote excess hair growth and acne. Most women with PCOS are overweight.

PCOS is the most common cause of infertility among women in the United States. If affects approximately 6 to 10 percent of women in childbearing age, which translates to between 3.5 and 5 million women.

Type 2 and polycystic ovary syndrome can share a common trait: insulin resistance

PCOS and Type 2

Type 2 diabetes and PCOS may share in a common root: Insulin resistance. Insulin resistance is a condition in which the body is unable to use insulin effectively. It is thought to be the most common cause of type 2 diabetes. Most women with PCOS have insulin resistance, regardless of whether they are underweight, normal weight or overweight.

Women who have PCOS are at risk for type 2 diabetes. Research indicates that 30 to 50 percent of overweight women with PCOS develop either impaired glucose tolerance or type 2 diabetes by the age of 30. Impaired glucose tolerance is a condition which blood glucose is high, but not high enough to prompt a diagnosis of diabetes.

Sometimes a patient with PCOS is diagnosed in her teens-perhaps by a gynecologist who’s able to piece together disparate symptoms, or by a dermatologist who’s “particularly aware of what male hormones can do to the skin,” explains Walter Futterweit, M.D., a clinical professor of medicine in the division of endocrinology at Mount Sinai School of Medicine, in New York City. Other women don’t discover they have PCOS until they have trouble conceiving a child.

But new research suggests that PCOS is much more than just a fertility problem. Scientists have discovered that women with the disorder are unable to use insulin efficiently. “PCOS is a metabolic disturbance with far-ranging health effects, increasing a woman’s risk of diabetes, heart disease and endometrial cancer,” says John Nestler, M.D., professor of medicine and chairman of the division of endocrinology and metabolism at Virginia Commonwealth University, in Richmond.

Fortunately, once diagnosed, the disorder can be controlled. Mild cases can be managed with appropriate diet and exercise to help control the metabolic problem at its root. Drugs have proved effective in helping to regulate the menstrual cycle, counter excess hair growth, even to restore fertility.

Being informed is the key. There are more resources for the disorder now than when Kushnick was looking twelve years ago-thanks, in part, to a growing network of PCOS women. “I started chatting with them over the phone, and followed up with packets of medical literature I’d collected about PCOS,” say Kushnick. Soon she was overwhelmed with requests.

Today, she heads the PCOS support group of the American Infertility Association, a nonprofit organization based in New York. Last October, she chaired a conference to educate patients on PCOS at Mount Sinai.

Doctors need to be informed, too. “Traditionally, reproductive disordered have not been a part of general medical training,” says Andrea Dunaif, M.D., an internist endocrinologist specializing in reproduction at Brigham and Women’s Hospital, in Boston. “A lot of obstetricians, gynecologists and internists tell PCOS women they’re too fat, put them on the Pill, and that’s it. There’s often a lack of appreciation of the long-term consequences.”

Are you at risk?

Though the underlying cause of PCOS remains a mystery, medical researchers believe that insulin resistance sets off a chain reaction that throws hormones out of kilter. As the disorder progresses, certain cells in the body grow less responsive to insulin and blood-sugar levels climb, which causes the pancreas to step up insulin production. In turn, the excess insulin stimulates the ovaries and adrenal gland to churn out testosterone and other androgens, which can disrupt ovulation. Depending on a woman’s sensitivity to male hormones, she may develop acne and male-pattern hair growth or loss. Failure to properly utilize insulin can also slow metabolism, which helps explain why so many PCOS women are overweight says Dunaif. At the same time, she notes, it’s likely the male hormones increase appetite.

But that’s not the worst of it. A PCOS woman continues to produce estrogen, but stops manufacturing progesterone. This imbalance causes the lining of the uterus to continue thickening, a condition that can invite endometrial cancer. Estrogen also stimulates the pituitary gland to release luteinizing hormone (LH), which signals the ovaries to release an egg. In normal functioning, after the egg is released, levels of LH drop; in women with PCOS, they remain elevated.

PCOS can culminate in diabetes and cardiovascular disease. Women with the disorder tend to have low HDL’s (good cholesterol), high LDL’s (bad cholesterol) and elevated triglycerides-factors that make them prime candidates for heart attack and stroke.

Experts advised any woman with an irregular menstrual cycle to be evaluated for PCOS. Family history of the disease is also a risk factor. In a study of around one hundred families, Dunaif found 50 percent of sisters of PCOS women either have the disorder of show signs of it.

PCOS and You

At present, researchers are not sure how many women with diabetes have PCOS, but it seems likely that PCOS occurs in women with diabetes at least as frequently as it does in the general population, if not more. Some studies suggest that certain ethnic groups such as African Americans or Latinos may be at greater risk for the development of PCOS than the general population.

Many women with diabetes have decreased ovulation and menstrual periods and these conditions may be related to a number of factors that have nothing to do with PCOS. Nonetheless, if you have irregular menstrual periods or if you have excess hair growth, you should tell your doctor. Because type 2 diabetes, infertility, excess hair growth, high blood pressure, and abnormal lipids can all be interrelated under the umbrella of insulin resistance, ask your doctor to check your blood pressure and cholesterol as well.

In all, PCOS and the infertility it causes are just two symptoms of insulin resistance. Therefore, treating and overcoming insulin resistance may improve your diabetes control; if you’ve had trouble conceiving, it may help you with that problem as well.

John Nestler, M.D. is professor and chairman of the Division of Endocrinology and Metabolism at Virginia Commonwealth University’s Medical College of Virginia in Richmond.


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