To compare the efficacy and safety of ASP1941 + metformin with metformin alone in Asian subjects with type 2 diabetes mellitus.

Inclusion Criteria:

• Diagnosed as type 2 diabetes mellitus patient at least 12 weeks before the study
• Stable diet and exercise program for at least 8 weeks before the study
• On a stable dose of at least 1500 mg/day metformin monotherapy or at least 1000 mg/day metformin monotherapy for the subject who can not titrate up to 1500 mg/day due to safety concern of metformin
• BMI of 20.0 to 45.0 kg/m2
• A HbA1c value between 7.0 and 10.0% at screening AND does not meet any of discontinuation criteria on fasting plasma glucose

Exclusion Criteria:

• Type 1 diabetes mellitus
• Proliferative diabetic retinopathy
• Receiving insulin within 12 weeks prior to the study
• History of clinically significant renal disease(s)
• Significant dysuria caused by a neurogenic bladder or a benign prostate hypertrophy etc.
• Urinary tract infection or genital infection
• Continuous use of systemic corticosteroids, immunosuppressants, or loop diuretics
• History of cerebrovascular attack, unstable angina, myocardial infarction, angioplasty, serious cardiac diseases within 12 weeks prior to the study
• Severe infection, serious trauma, or perioperative subject
• Known or suspected hypersensitivity to ASP1941
• History of treatment with ASP1941
• Participated in another clinical study, postmarketing study or medical device study within 12 weeks before the study
• Serum creatinine value exceeding the upper limit of normal range
• Urinary microalbumin/urinary creatinine ratio >300 mg/g

Access to anonymized individual participant level data will not be provided for this trial. Further details on Astellas' data sharing policy can be found at https://www.clinicaltrials.astellas.com/transparency/.