This is a prescription tablet that, when taken orally and combined with a proper diet and exercise, will help control blood sugar levels in those with Type 2 diabetes. Glucophage is not recommended for the treatment of Type 1 diabetes, according to Glucophage.com. The most serious side effect associated with the use of Glucophage is lactic acidosis, which brings about symptoms that include rapid breathing, sweating and severe stomach pain. Other common side effects include nausea, headaches, indigestion, mild stomach pain and diarrhea, according to MayoClinic.com.