For women with type 2 diabetes who have trouble getting pregnant, an underlying condition that was present before diabetes could be the culprit. Polycystic ovary syndrome (PCOS) is the leading cause of ovulation-related infertility. It’s characterized by irregular menstruation (missed, infrequent, or heavy periods) and accompanied by one or more other symptoms that include acne; abnormal hair growth on the face, back, and other areas (hirsutism); and cysts growing on the outside of the ovaries. Some women also have skin tags or dark patches of skin on the neck or thighs (acanthosis nigricans), which usually signal not just PCOS but also insulin resistance. PCOS indicates a higher risk for type 2 diabetes, abnormal cholesterol levels, cardiovascular disease, and endometrial and ovarian cancers. It also can lead to infertility and puts pregnant women at a higher risk for gestational diabetes, miscarriage, pre-term birth, and preeclampsia.

About 5 to 10 percent of women ages 18 to 44 are affected by PCOS, according to a study published in Clinical Obstetrics and Gynecology in 2007. (The statistic is hazy partly because many women go undiagnosed for years, and partly because the criteria for diagnosis have changed over time.) Usually, PCOS and insulin resistance come first and may later advance to type 2 diabetes. “The majority of women with PCOS don’t have diabetes [when they’re diagnosed],” says Shahab Minassian, MD, chief of reproductive endocrinology and infertility at Reading (Pa.) Hospital and Medical Center and former codirector of Drexel University’s Center for PCOS.

Once diagnosed, women with PCOS who do not suffer from other fertility issues have a good chance for a successful pregnancy: Minassian estimates the success rate among his younger infertile patients to be 60 to 70 percent. For women in their late 30s, that rate might drop to about 50 percent, he says. Losing weight often mitigates the condition. Doctors may prescribe the diabetes drug metformin as a frontline treatment for women with PCOS who are trying to conceive. Studies have shown that boosting insulin sensitivity with metformin helps to regulate periods, correct problems with infertility, and reduce abnormal hair growth; in pregnant women with PCOS, there is some early evidence that metformin use may decrease miscarriage rates. Women trying to get pregnant may need additional fertility medication; clomiphene (Clomid) is the most commonly prescribed option. (In women with PCOS who are not trying to get pregnant, oral contraceptives are prescribed to help regulate menstruation.)

In general, women with diabetes and PCOS who maintain good blood glucose control, watch their weight, and get appropriate treatment should have reason to feel optimistic about success in pregnancy. “Generally, they have a good prognosis, but sometimes it’s a long road,” says Richard Legro, MD, of the Department of Obstetrics and Gynecology at the Penn State University College of Medicine. “I think there’s still a lot to be discovered about PCOS.”