A Study to Evaluate the Effect of ASP1941 in Adult Patients With Type 2 Diabetes Mellitus

Inclusion Criteria: * Subject has been diagnosed with type 2 diabetes * Subject has a HbA1c value between 6.8 and 9.5% * Subject has never, is not currently taking anti-diabetic medication OR is receiving a single anti- diabetic agent or low-doses two anti-diabetic medications and is willing to discontinue them during the study * Subject is on a stable diet and exercise program * Female subject is not pregnant and agrees to use an acceptable form of contraception throughout the duration of the study Exclusion Criteria: * Subject has type 1 diabetes mellitus * Subject is using insulin therapy * Subject has a serum creatinine higher than upper limit of normal * Subject has an ALT and/or AST value higher than 3 times upper limit of normal or a total bilirubin value more than 2 times upper limit of normal * Subject has persistent, uncontrolled severe hypertension as indicated by a systolic blood pressure \>180 mmHg or a diastolic blood pressure of \>110mmHg * Subject has had significant cardiovascular disease such as myocardial infarction or a vascular intervention (e.g., angioplasty or stent) in the last 3 months * Subject is known to have hepatitis or be a carrier of hepatitis B surface antigen, hepatitis C virus antibody or is known positive for HIV1 and/or HIV2 * Subject has a history of lactic acidosis * Subject has a history of drug and alcohol abuse/dependency within last 12 months * Subject has had a malignancy in the last 5 years, except for successfully treated basal or squamous cell carcinoma of the skin or of the cervix * Subject has a symptomatic urinary tract infection or genital infection * Female subject is lactating * Subject has an unstable medical or psychiatric illness