Comparison of Fasiglifam (TAK-875) to Placebo and Sitagliptin in Combination With Metformin in Participants With Type 2 Diabetes

Inclusion Criteria: 1. The participant is male or female and 18 years of age or older with a historical diagnosis of type II diabetes mellitus. 2. The participant meets one of the following criteria: 1. The participant has an HbA1c level ≥7.5 and \<10.5%, and has been on a stable daily dose of ≥1500 mg (or documented maximum tolerated dose \[MTD\]) of metformin for at least 2 months prior to Screening. This participant will immediately enter the Placebo Run-in Period according to Study Schedule A, or; 2. The participant has an HbA1c level ≥7.5 and \<10.5%, and has been on a stable daily dose of \<1500 mg of metformin without documented MTD for at least 2 months prior to Screening. After completing the Screening Visit, this participant will have their metformin dose immediately increased to ≥1500 mg (or MTD) for an 8-week Titration Period according to Study Schedule B. Following this 8-week period, the participant must qualify for entry into the Placebo Run-in Period by completing the Week -3 procedures including having an HbA1c level ≥7.5 and \<10.5%. 3. The participant has had no treatment with antidiabetic agents other than metformin within 2 months prior to Screening (Exception: if a participant has received other antidiabetic therapy for ≤7 days within the 2 months prior to Screening). 4. The participant has a body mass index (BMI) ≤45 kg/m² at Screening. 5. Participants regularly using other, non-excluded medications, must be on a stable dose for at least 4 weeks prior to Screening. However, PRN (as needed) use of prescription or over-the-counter medications is allowed at the discretion of the investigator. 6. The participant is able and willing to monitor glucose with a home glucose monitor and consistently record his or her own blood glucose concentrations and complete subject diaries. Exclusion Criteria: 1. The participant donated or received any blood products within 12 weeks prior to Screening or is planning to donate blood during the study. 2. Hemoglobin ≤12 g/dL (≤120 g/L) for males and ≤10 g/dL (≤100 g/L) for females at Screening Visit. 3. The participant has systolic blood pressure ≥160 mm Hg or diastolic pressure ≥95 mm Hg at Screening Visit. (If the participant meets this exclusion criterion, the assessment may be repeated once at least 30 minutes after the initial measurement.) 4. The participant has a history of laser treatment for proliferative diabetic retinopathy within 6 months prior to Screening. 5. The participant has had treatment for gastric banding or gastric bypass surgery within one year prior to Screening. 6. The participant had coronary angioplasty, coronary stent placement, coronary bypass surgery, myocardial infarction, unstable angina pectoris, clinically significant abnormal ECG, cerebrovascular accident or transient ischemic attack within 3 months prior to or at Screening.