Metformin (brand name Glucophage) is approved for type II diabetes. Like many drugs, though, it has found other uses besides that for which it is approved. One such use is for women with PCOS who wish to get pregnant.

What does PCOS have to do with diabetes? The key here is insulin. In type II diabetes, the body just doesn't make enough insulin or use what it has effectively. In PCOS, women are "insulin resistant," wherein their bodies need lots of insulin to move the glucose into the cells. High insulin leads to increased production of androgens, or male hormones. This leads to a negative feedback loop and decreased LH production, anovulation, and even cessation of menstruation. Some women notice increased facial hair and acne.

Women with PCOS who are overweight may find their problem goes away with weight loss, but that may not be enough. And there are many women with PCOS who are not overweight, which points to a genetic factor for PCOS.

That's where metformin comes into play. It effectively lowers insulin in non-diabetic patients. Lowering insulin leads to normalization of the androgen levels and restoration of a normal menstrual cycle. Unlike a diabetic who would monitor her blood glucose level, a patient with PCOS is simply looking for a regular menstrual cycle and hormone levels. The doctor will check those with a blood test. You, of course, would be tracking your menstrual cycle.

No drug is completely harmless. Metformin typically causes stomach upset in the first few weeks of treatment. Taking it with food helps. If you become pregnant while taking it, many doctors will continue the medication. Metformin is classified as Category B, which means that there are no human data to show that it is safe, but there are also no animal data showing fetal abnormalities.

Unfortunately, women with PCOS have a higher risk of miscarriage. Metformin has not been proven to improve the outcomes for women with PCOS because that would require a placebo-controlled study. Any study in pregnant women is hard to do! The reason why these women have more miscarriages may be due to abnormal blood clotting caused by high insulin levels. They may be better off taking baby aspirin or other anti-clotting medication instead. Again, there are no studies to guide us here--just talk to your doctor.