Pathophysiology of type 2 diabetes is known as insulin resistance and progressive beta cell dysfunction.~Combination therapy with biguanides, glucagon-like peptide-1(GLP-1) agonists or dipeptidyl peptidase-4 inhibitor(DPP4I) and thiazolidinediones(TZD) seems reasonable theoretically, for their effects on different pathophysiologic defects.~Current treatment guidelines recommend a stepwise approach starting with lifestyle modification or lifestyle modification + metformin monotherapy, with recent focusing on patient individualization.~In Korea, Korean Diabetes Association also recommends stepwise approach and at the same time, emphasizes on the initial aggressive treatment including oral combination or insulin therapy according to HbA1c level to achieve target goal <6.5%.~Guide to the efficacy, timing, options of combination therapy is not clearly defined due to lack of sufficient evidences yet.~There is no clear report to demonstrate the clinical benefit of initial TZD and DPP4I combination therapy in the Korean.~Thus it is reasonable to study the effect of combination therapy in the patients with sub-optimal glucose control with metformin therapy only, comparing various combination options metformin with DPP4I only, TZD only, or both.~The hypothesis of this study is that combination therapy of alogliptin and pioglitazone added on the metformin has superior effect on HbA1c reduction than metformin and either alogliptin or pioglitazone in 6 month treatment.
This study evaluate the efficacy and safety of alogliptin and pioglitazone combination therapy in comparison with either alogliptin or pioglitazone on glucose control in the metformin-treated type 2 diabetic patients in Korea.