Study to Assess Safety & Efficacy of Sitagliptin as Initial Oral Therapy for Treatment of Type 2 Diabetes Mellitus in Pediatric Participants. (MK-0431-083)

Sitagliptin 100 mg tablet administered orally once daily

Metformin 500 mg tablets administered orally starting at 500 mg/day and uptitrated by 500 mg every week to a final dose of 1000 mg twice daily

Matching placebo to sitagliptin 100 mg tablet administered orally once daily

Matching placebo to metformin 500 mg tablets, 2 tablets administered orally twice daily

Participants in the sitagliptin arm who require glycemic rescue will receive metformin during Weeks 0-20 and Weeks 20-54. Participants in the placebo arm who require glycemic rescue will receive metformin during Weeks 0-20. Participants in the placebo arm who have switched to metformin during Weeks 20-54 and require glycemic rescue will receive sitagliptin.

Participants who require glycemic rescue after Glycemic Rescue 1 will receive open-label insulin. Participants on background insulin therapy will have the dose of their background insulin up-titrated.