The study will include screening and 24-week treatment period. Subjects entering the study have been on a stable dose of at least 1000 mg/day metformin monotherapy for at least 8 weeks (56 days) prior to Visit 1. For randomization, subject will be stratified by the site and the administration of renin-angiotensin system inhibitors (angiotensin receptor blockers and/or angiotensin-converting-enzyme inhibitors) at Visit 2. Subjects will be centrally randomized to either ipragliflozin/metformin group or glimepiride/metformin group and receive 24-week treatment by each group