Glycemic Effectiveness of Metformin-Based Dual-Combination Therapies with Sulphonylurea, Pioglitazone, or DPP4-Inhibitor in Drug-Naïve Korean Type 2 Diabetic Patients

BACKGROUND: This study compared the glycemic effectiveness of three metformin-based dual therapies according to baseline hemoglobin A1c (HbA1c) to evaluate the appropriateness of the guideline enforced by the National Health Insurance Corporation of Korea for initial medication of type 2 diabetes (T2D). METHODS: This prospective observational study was conducted across 24 weeks for drug-naïve Korean T2D patients with HbA1c greater than 7.5%. Subjects were first divided into three groups based on the agent combined with metformin (group 1, gliclazide-modified release or glimepiride; group 2, pioglitazone; group 3, sitagliptin). Subjects were also classified into three categories according to baseline HbA1c (category I, 7.5%≤HbA1c<9.0%; category II, 9.0%≤HbA1c<11.0%; category III, 11.0%≤HbA1c). RESULTS: Among 116 subjects, 99 subjects completed the study, with 88 subjects maintaining the initial medication. While each of the metformin-based dual therapies showed a significant decrease in HbA1c (group 1, 8.9% to 6.4%; group 2, 9.0% to 6.6%; group 3, 9.3% to 6.3%; P<0.001 for each), there was no significant difference in the magnitude of HbA1c change among the groups. While the three HbA1c categories showed significantly different baseline HbA1c levels (8.2% vs. 9.9% vs. 11.9%; P<0.001), endpoint HbA1c was not different (6.4% vs. 6.6% vs. 6.0%; P=0.051). CONCLUSION: The three dual therapies using a combination of metformin and either sulfonylurea, pioglitazone, or sitagliptin showed similar glycemic effectiveness among drug-naïve Korean T2D patients. In addition, these regimens were similarly effective across a wide range of baseline HbA1c levels.