Metformin is the first-line medication for the treatment of type 2 diabetes.  Using metformin alone, with a type of oral antidiabetic medicine called a sulfonylurea, or with insulin, will help to lower blood sugar when it is too high and help restore the way you use food to make energy.  It is not associated with weight gain. 

Brand Names:  Glumetza, Glucophage, Fortamet, Riomet, and Glucophage XR

Drug class: Diabetes medication

The more common side effects of metformin include:

• heartburn
• stomach pain
• nausea or vomiting
• bloating
• gas
• diarrhea
• constipation
• weight loss
• headache
• unpleasant metallic taste in mouth