This study is to assess the effect of renal function on the efficacy and safety of ASP1941 in type 2 diabetic patients with mild to moderate renal impairment.

This study will be conducted in patients with type 2 diabetes mellitus and mild to moderate renal impairment who have inadequate glycemic control on an exercise program and stable diet, or one oral hypoglycemic agent.

The severity of the reduction in renal function in each subject will be classified according to the glomerular filtration rate (GFR) estimated using the Japanese GFR estimation equation. Subjects will start with a screening period, followed by a single-blind placebo run-in period, and will be randomized to the ASP1941 groups or the placebo group at a ratio of 2:1. For randomization, subjects will be stratified according to the severity of the reduction in renal function. In a treatment period, subject will receive study drug or placebo for 24 weeks under double-blind conditions.

At 24 week, subjects who are willing to continue participation in the study will receive study drug for another 28 weeks in an open label condition. ASP1941 can be increased. After completion of the study drug administration, a follow-up period will be provided.

Inclusion Criteria:

• type 2 diabetes mellitus patient
• subject has been on an exercise program and stable diet, or one oral hypoglycemic agent (alpha-glucosidase inhibitor, sulfonylurea agent and pioglitazone)
• estimated GFR value based on the Japanese GFR estimation equation of ≥ 30 mL/min/1.73 m2 and < 90 mL/min/1.73 m2
• HbA1C value between 6.5 and 8.5%
• body mass index (BMI) 29.0 - 45.0 kg/m2

Exclusion Criteria:

• type 1 diabetes mellitus patients
• proliferative diabetic retinopathy
• subject has received insulin within 12 weeks before the study
• subject has a chronic disease which requires the continuous use of adrenocortical steroids, immunosuppressant, and loop diuretic
• serum creatinine > upper limit of normal
• proteinuria (albumin/creatinine ratio > 300mg/g)
• dysuria and/or urinary tract infection, genital infection
• significant renal, hepatic or cardiovascular diseases
• severe gastrointestinal diseases

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/.