PCOS & Insulin-Sensitising Drugs (Metformin)

PCOS can lead to a resistance to insulin, causing the body to produce excessively high levels of insulin in an attempt to compensate. This higher level of insulin is known to cause abnormal cholesterol and lipid levels, obesity, irregular periods, higher levels of androgens, infertility due to disturbance of ovulation and an increased likelihood of diabetes.

To help combat these problems, women with PCOS may be prescribed Metformin. Metformin is a type of drug known as an 'insulin-sensitising agent', which lowers the blood sugar level, in turn reducing the excessively high insulin.

Study Findings

There are actually very few studies that have been carried out and published concerning the use of insulin sensitising drugs as a treatment for PCOS. These suggest that it may well be useful in several areas: helping weight reduction, improving irregular periods (70%), normalising blood cholesterol and leading to ovulation.

One study looking at ovulation in particular found that, compared to no treatment, 34% of women ovulated taking metformin (compared to 4% who did not receive it) and when this was combined with clomifene it was as high as 90% (as compared to 8% in those who only received clomifene). These studies contained overweight women with PCOS - its role in treating women of normal weight has not been investigated. The most common side effects during treatment are diarrhoea, nausea, vomiting and abdominal bloating.

Shortcomings of the Studies

The studies that are available concerning the insulin-sensitising drugs are very exciting and will hopefully pave the way for a longer-term treatment for this disease, which can affect many different areas of a woman's life. It is important to realise, though, that the investigation is still at a very early stage. Long-term effects are not known - the longest follow up so far is for around 6 months of use.

Considering its use as a treatment for infertility, the studies are small compared to more traditional treatments, containing only up to 35 patients receiving metformin. Most studies are not comparative, in that they did not compare 'treatment' with 'no treatment', an extremely important point. The outcome of the studies has looked at the effect on ovulation rather than actual pregnancy or birth rates. We know from clomifene that only half of women who ovulate actually get pregnant - what is the figure for these newer drugs?

What the Future Holds

Because of the lack of research using these drugs, many doctors are awaiting further studies to confirm their initial apparent success and identify potential side effects before jumping in and prescribing them. This is a safe and sensible approach. There may be specific cases when their use is considered appropriate at this stage, and this is something for an individual doctor to decide with the patient's full understanding of the present situation.