This is important, especially now that there are several different drug classes from which to choose. The first type of therapy is still diet and exercise. They do not directly lower blood sugar but work instead to prevent hyperglycemia. Each type of oral hypoglycemics works by a different mechanism, thus each has pros and cons. For example, sulfonylureas stimulate insulin release but tends to cause weight gain and can trigger hypoglycemia.
Metformin reduces glucose production in the liver and increases glucose sensitivity.
It does not cause hypoglycemia or weight gain. However, some patients experience diarrhea, and there is a slight risk of developing lactic acidosis. Acarbose slows the intestinal absorption of carbohydrates but it is less effective than the other two at lowering blood sugar, and many patients have problems with gas or other GI side effects. The third step in diabetes therapy is combination therapy with oral agents from different classes or with an oral agent plus insulin. Usually sulfonylureas are combined with metformin, acarbose, or insulin.