I've been taking Metformin for about eight years now. I still have an issue with diarrhea at times. It's very uncomfortable and I don't really know when it's going to happen. I usually keep something like pepto bismol on hand. I wish I could say that it gets better, but I don't think it will. : (
Sorry I can't be of much help to you. If you find something that works, please let me know.