• Q: Why does metformin make my stomach cramp? • A: Metformin (Glucophage) is a medication used for the treatment of diabetes or high blood sugar. It works by decreasing the production of glucose by the liver. The main side effects of metformin (Glucophage) are gastrointestinal in nature and include diarrhea, nausea, vomiting and flatulence. These side effects can be diminished by taking metformin (Glucophage) with food. These side effects also tend to improve over time, so if it is a new medication, the side effects will likely get better. Your healthcare provider will be able to provide you with more information.