Many classes of oral antihyperglycemic agents are available for the treatment of type 2 diabetic patients. These classes improve glucose metabolism by different mechanisms, and their effects are additive. Therapy with lifestyle modification and a single oral antihyperglycemic agent infrequently achieves target glycemic goals, and, if it does, the effect is usually not sustained. A more rational approach would seem to be therapy with combinations of drugs with different mechanisms of action. Initial therapy might be with submaximal concentrations of two drugs. As the diabetic abnormalities progress, maximal concentrations of the drugs and addition of other classes of oral agents or insulin may be needed to maintain the target glycemic goal. In choosing combinations of oral antihyperglycemic agents, their effects on the components treatment of type 2 diabetic patients. These classes improve glucose considered, as must the specific effects of the agents on glucose metabolism.