Oral combination therapy for type 2 diabetes.

For patients with type 2 diabetes, oral monotherapy may be initially effective for controlling blood glucose, but it is associated with a high secondary failure rate. (Primary failure is frequent only in patients with high baseline blood glucose at the time of beginning monotherapy, whereas secondary failure is to be expected in the course of the disease.) The different classes of oral agents used to treat type 2 diabetes have complementary mechanisms of action, and their use in combination often results in blood glucose reductions that are significantly greater than those that can be obtained with maximal doses of any single drug. A wide range of combinations (e.g. sulfonylurea plus metformin, a thiazolidinedione, or acarbose; metformin plus a thiazolidinedione or acarbose) have been used effectively to achieve glycemic control in patients in whom oral monotherapy has failed. The high secondary failure rates for oral monotherapy - and, moreover, the high primary failure rate in patients with very high blood glucose at diagnosis - coupled with the effectiveness of combination treatment, support the suggestion that multiple-drug regimens be considered for initial pharmacologic treatment in patients with symptomatic type 2 diabetes whose blood glucose is not controlled by diet alone.