A Study of the Safety and Effectiveness of a R256918 in Patients With Type 2 Diabetes

5 mg twice daily for 12 weeks

10 mg twice daily for 12 weeks

15 mg twice daily for 12 weeks

twice daily for 12 weeks

Participants will continue taking metformin at the same dose and according to the same dosing regimen as before the study.

Participants will receive dietary counseling at Screening, Week 4, 8, 12, and will be instructed to remain on a calorically appropriate diet with a maximum of 30% of calories derived from fat (in accordance with local practice guidelines for the treatment of type 2 diabetes mellitus) during the entire study.