I have been PCOS and have been on regular Metformin since July 2010 and I am down 60lbs! I have been on my regular dosage of 850mg twice a day since November 2010. I recently started having issues, including horrible headaches and throwing up (maybe once a week). I called my doctor the other day to tell her and she switched me to the extended release version, which I have not picked up from the pharmacy yet. As far as my PCOS symptoms go, as long as I watch what I eat and remember to take my pill with a meal, I do not have issues with my blood sugar levels.
I know this sounds vain, but the whole reason I am posting this is to find out if anyone has experienced weight gain on the extended release? I am willing to suffer through the occasional headaches, etc, if the weight stays off.