Always worth mentioning it to the nurse just to let them know that it isn't as nice to take as they make out. Slight tummy ache was my warning, the worst diarrhea of my life was the reality along with a doctor who said it wasn't the metformin, I had IBS.I recently have had my metformin increased and its left me with quite a bad tummy, will this sort its self out? Or should I speak to my diabetic nurse? Many thanks x