I take 1000mg of metformin twice a day to control my IR/PCOS. I had TERRIBLE GI effects for about the first month that I was taking it but after about a month they subsided and I feel much better. I think it's one of those YMMV things, my mother takes it for her diabetes and she has never had any of the side effects! I have to say that I did start getting my periods again after the second month I was taking it so it does seem to be working on me.