New oral therapies for type 2 diabetes.

Over the past few years, several oral agents for the treatment of type 2 diabetes have become available in the United States. Metformin, a biguanide that has been used for decades in other countries throughout the world, improves glycemic control without exacerbating hyperinsulinemia or promoting weight gain. This agent has recently been reintroduced in the United States. Acarbose is an alpha-glucosidase inhibitor that improves glycemic control by decreasing the intestinal absorption of glucose, thereby decreasing postprandial glucose elevations. The use of metformin and acarbose may be limited by their side effects and potential risks, especially the risk of lactic acidosis with metformin. The third newly available agent, troglitazone, has been shown to improve insulin sensitivity. Combinations of metformin, acarbose and troglitazone may facilitate improved glycemic control without the use of insulin, or they may allow sulfonylurea or insulin dosages to be reduced, in this way minimizing the adverse effects of hyperinsulinemia. Unfortunately, current oral therapies do not prevent the inevitable decline in glycemic control that occurs during the natural history of type 2 diabetes.