I've been on Metformin to treat PCOS (Poly-Cystic Ovarian Syndrome)--yet another thing linked to insulin resistance. All I have to say is beware the gastro-intestinal side effects. That med had me running to the bathroom a lot and not in a good way. To be graphic, stomach cramps and the trots. Eventually ended up on the extended release version (Glucophage XR in the US at that time) which made things not perfect, but much better.

The good side effect was that after going on the med, I started to lose weight. A little bit of weight loss got me motivated to change my diet, exercise, etc. Ended up around 90 lbs lighter than I started.

Upshot of this whole thing is if you have any problems on the straight Metformin, ask right away for the XR.