This study evaluates the efficacy and safety of adding the SGLT-2 inhibitor DA5221-T to the combination therapy of DA5221-B1 and the DPP-4 inhibitor DA5221-B2 in patients with type 2 diabetes who have inadequate blood glucose control. The study focuses on assessing the effectiveness and safety of the triple combination therapy.

Inclusion Criteria:

1. Patients with type II diabetes mellitus aged 19 years or older
2. Patients who had taken DA5221-B1 and DA5221-B2(or another DPP-4 inhibitor is allowed) combination therapy at the same dose for at least 8 weeks prior to the screening visit
3. Patients with fasting plasma glucose≤270mg/dL at the screening visit
4. Patients with 18.5kg/m^2≤BMI≤40kg/m^2 at the screening visit
5. Patients who have signed an informed consent themselves after receiving detailed explanation about the clinical study

Exclusion Criteria:

1. Patients with type 1 diabetes, secondary diabetes, gestational diabetes, diabetic coma or -pre-coma, metabolic acidosis including lactic acidosis and diabetic ketoacidosis
2. Patients with a medical history of New York Heart Association(NYHA) class III~IV heart failure or with congestive heart failure, acute and unstable heart failure
3. Patients with severe infectious disease or severe traumatic systemic disorders
4. Patients with hypopituitarism or adrenal insufficiency, pulmonary infarction, severe pulmonary dysfunction and other hypoxemia
5. Patients with galactose intolerance, lapp lactase deficiency, glucosegalactose malabsorption