Quadruple Oral Combination Therapy for Type 2 Diabetes Mellitus : Glycemic Control by Thiazolidinedione (TZD) or Sodium Glucose Co-transporter 2 (SGLT-2) Inhibitor as an add-on Therapy in Type 2 Diabetes Mellitus After Failure of an Oral Triple Antidiabetic Regimen

Pioglitazone 15mg (Acpio®, once daily, regardless of meal time, for 24 weeks) will be added for T2DM(type 2 diabetes mellitus) patients who had inadequate glycemic control (7% \<HbA1c ≤ 10%) with triple therapy (metformin, DPP-4 inhibitors, sulfonylurea). At visit 3 (after 12 week-treatment), patients whose HbA1c level is more than 7.0% will be prescribed increased dosage of pioglitazone : from 15mg to 30mg

Empagliflozin 10mg (Jardiance®, once daily, regardless of meal time, for 24 weeks) will be added for T2DM patients who had inadequate glycemic control (7% \<HbA1c ≤ 10%) with triple therapy (metformin, DPP-4 inhibitors, sulfonylurea). At visit 3 (after 12 week-treatment), patients whose HbA1c level is more than 7.0% will be prescribed increased dosage of empagliflozin : from 10mg to 25mg