Study of Sitagliptin for the Treatment of Type 2 Diabetes Mellitus With Inadequate Glycemic Control on Insulin (MK-0431-260)

Sitagliptin 100 mg tablet once daily for 24 weeks

Placebo to sitagliptin once daily for 24 weeks

Participants on insulin glargine or another insulin regimen for at least 10 weeks prior to screening will continue or switch to open-label insulin glargine once-daily in the evening for the duration of the study.

Participants on metformin oral tablet(s) at a dose of at least 1500 mg/day for at least 10 weeks prior to screening will continue receiving metformin at their current dose for the duration of the study.