A Study to Evaluate the Effect of add-on Pioglitazone or Dapagliflozin in Participants With Type 2 Diabetes Mellitus Inadequately Controlled by DPP-4 Inhibitor and Metformin Therapy

Inclusion Criteria: 1. The subject is a regular outpatient with an has a historical diagnosis of type 2 diabetes. 2. The subject has metabolic syndrome as jointly defined by the International Diabetes Federation (IDF); National Heart, Lung, and Blood Institute (NHLBI) / American Heart Association (AHA); and International Association for the Study of Obesity (IASO). If any 3 of the following 5 risk factors are present, metabolic syndrome can be considered: * High waist circumference: male ≥ 90 cm, female ≥ 85 cm. * High TGs (drug treatment for high TGs is an alternate indicator): ≥ 150 mg/dL (1.7 mmol/L). * Low HDL-C (drug treatment for low HDL-C is an alternate indicator): \< 40 mg/dL(1.0 mmol/L) in males, \< 50 mg/dL (1.3 mmol/L) in females. * High blood pressure (antihypertensive drug treatment in a subject with a history of hypertension is an alternate indicator): Systolic ≥ 130 mmHg and/or diastolic ≥ 85 mmHg. * High fasting glucose (drug treatment of high glucose is an alternate indicator): ≥ 100 mg/dL. 3. The subject has been receiving a stable dose of DPP-4 inhibitor + metformin therapy with diet and exercise for ≥ 3 months prior to Randomization. 4. The subject has a HbA1c value between 7.0 and 11% inclusively within 28 days of Randomization via central laboratory test or after run-in period for 4 weeks via central laboratory test. Exclusion Criteria: 1. The subject has type 1 diabetes, diabetic ketoacidosis, diabetic coma or diabetic precoma. 2. The subject has an active bladder cancer or a history of bladder cancer. 3. The use of any medications ie, oral or systemically injected glucocorticoids (including intra-articular injection), weight-loss drugs, insulin or other anti-diabetic drugs except DPP-4 inhibitor and metformin, within 3 months prior to randomization. Strong Cytochrome P450 2C8 (CYP2C8) inhibitors (eg, gemfibrozil, montelukast, quercetin, phenelzine) and CYP2C8 inducers (eg, rifampin) that in the opinion of the Investigator or Sponsor require treatment contraindicated during the study. The diuretics, angiotensin receptor blockers (ARBs), angiotensin-converting enzyme (ACE) -inhibitors and nonsteroidal anti-inflammatory drugs (NSAIDs) are to be used per product label with close monitoring under Investigator's supervision. 4. Has genetic problems such as galactose intolerance, Lapp lactose dehydrogenase deficiency or glucose-galactose uptake disorder, etc. 5. Has a history of alcohol abuse within 2 years prior to randomization.