Metformin, a medication for type 2 diabetes, decreases the liver’s glucose output and increases the muscles’ glucose uptake. Taken one to three times a day; extended-release (XR) formulations can be taken once daily. Possible side effects: nausea, upset stomach, diarrhea (can sometimes be avoided by taking with food or by using the extended-release formulations). Should not be taken by persons with decreased kidney function or certain other medical conditions. Medications available: metformin (Fortamet, Glucophage, Glucophage XR, Glumetza, Riomet).