RESEARCH TRIANGLE PARK, N.C. — Avandamet, a diabetes drug from GlaxoSmithKline, can now be used as an initial treatment for type 2 diabetes.

GSK said Tuesday that it had received Food and Drug Administration approval for Avandamet to be prescribed as an first-line treatment in conjunction with diet and exercise. Avandamet was approved in 2002 as a second-line therapy, or given when an initial therapy failed or stopped working.

The drug combines two agents, rosiglitazone, an insulin sensitizer, and metformin, a leading diabetes therapy, to help patients control their blood sugar.

Some 20 million Americans suffer from diabetes, and type 2 is the most common, afflicting between 90-95 percent of those diagnosed, National Institute of Health figures show. Type 2 diabetes is characterized by high blood glucose levels caused by either a lack of insulin or the body’s inability to use insulin efficiently, according to the American Diabetes Association.

“GlaxoSmithKline is committed to developing diabetes therapies to treat a disease that has reached epidemic proportions in the United States and throughout the world,” said Anne Phillips, vice president of Clinical for North America Cardiovascular-Metabolic at GSK, in a statement. “With the approval of Avandamet for use as initial therapy as an adjunct to diet and exercise, GSK offers this effective and convenient option now for initial treatment of type 2 diabetes. This combination of rosiglitazone and metformin can help patients get their blood sugar under control.”