Issue 135 Item 7 Safety and Efficacy of Metformin for PCOS is Still in Question

A leading British expert says caution is still needed as solid evidence about its efficacy is sparse. The insulin sensitising agent metformin has attracted a lot of attention as a treatment for polycystic ovary syndrome (PCOS) in recent years, but beware.

PCOS prevalence is increasing in the Western world, partly in tandem with increasing BMI and rates of insulin resistance, Dr. Adam Balen from the General Infirmary at Leeds said at a joint meeting of the Royal College of Obstetricians and Gynaecologists and the British Fertility Society.

Currently about 20% of couples seeking fertility treatment do so due to anovulation, and 85%-90% of those have PCOS. Metformin, which inhibits the production of hepatic glucose and increases the sensitivity of peripheral tissue to insulin, has garnered a lot of publicity as a treatment, but scientifically sound data is inadequate, says Dr. Balen.

There’s a huge amount of buzz around the drug and patients are asking to be prescribed it, but "all that’s come out of small studies," he said. Adequately powered clinical studies are lacking, while "there are other treatments for anovulatory infertility that have gone through the mill and the evidence is strong."

For patients who have been appropriately investigated by a reproductive physician, Dr. Balen is sure there is a role for metformin in women with PCOS.

"I think the good thing about metformin is that it has been around for a long time in the treatment of diabetes and appears to be a safe drug. Also, in the context of women wanting to get pregnant there doesn’t seem to be an increased risk to the foetus," he said. "But again, we need to have appropriately published evidence."

In an effort to fill in some of the research blanks, Dr. Balen and colleagues are conducting a randomized, placebo-controlled trial in 260 women, about 170 of whom have so far been recruited.

They are including women who have a BMI over 30, PCOS and irregular periods. The women take the drug or placebo for 6 months, and are given advice on diet and exercise.

"Metformin is also often projected as a drug that will help women to lose weight but there is no clear evidence that it helps lose weight," Dr. Balen added. "Many women will lose weight while taking metformin because they’ve also been given advice on diet and exercise at the same time."

The results of the trial are expected in about a year.