Metformin is also sold under the brand names Glucophage and Glucophage XR, and is found in pills that combine two types of antidiabetes medication, such as Glucovance and Metaglip (which combine metformin with a sulfonylurea drug) and Avandamet (a combination of metformin and rosiglitazone, a thiazolidinedione medication).
Metformin is a biguanide, a drug that reduces the amount of glucose that the liver makes and improves the body's use of insulin. The U.S. Food and Drug Administration approved it in 1995, but it has been used in Europe, Canada, and other countries for much longer.
Metformin has a long safety record
In 2006 the American Diabetes Association recommended it as the first drug of choice for patients, edging out sulfonylureas, a class of drug used since the 1950s that is more likely to cause weight gain and hypoglycemia.
Metformin's decade-long safety record may come as a relief for people who remember another drug in that class, phenformin. That drug was pulled from the U.S. market in the 1970s due to an increased risk of lactic acidosis, a potentially fatal buildup of lactic acid in the blood.
After the phenformin scare, many people were skittish about using a drug in the same class of medications, says Richard Hellman, MD, former president of the American Association of Clinical Endocrinologists. But after more than a decade of metformin's use in the U.S., those worries have been allayed. "It's a common mainstay; it's a very good drug," Dr. Hellman says.