Conditions: Diabetes Mellitus, Type 2
Allocation: RANDOMIZED | Intervention model: PARALLEL
Enrollment: 741
Healthy volunteers: no

Brief summary:
The purpose of this clinical study is to determine the safety and efficacy of an investigational drug in patients with type 2 diabetes mellitus.

Detailed description:

Arms:
arm 1: Phase A and B: Oral tablets of sitagliptin 100 mg Once a Day (q.d ) arm 2: Phase A and B: Oral tablets of sitagliptin 200 mg q.d arm 3: Phase A: Oral tablets of placebo matching sitagliptin 100 mg q.d. Phase B: Oral tablets of sitagliptin 100 mg q.d. arm 4: Phase A: Oral tablets of placebo matching sitagliptin 200 mg q.d. Phase B: Oral tablets of sitagliptin 200 mg q.d.

Interventions: intervention 1: Sitagliptin (MK0431) intervention 2: Sitagliptin intervention 3: Placebo intervention 4: Placebo intervention 5: Metformin - Rescue
Intervention descriptions: intervention 1: Phase A: Sitagliptin 100 mg once a day for 24 weeks. Phase B: Sitagliptin 100 mg once a day for 80 weeks. intervention 2: Phase A: Sitagliptin 200 mg once a day for 24 weeks. Phase B: Sitagliptin 200 mg once a day for 80 weeks. intervention 3: Phase A: Placebo matching Sitagliptin 100 mg once a day for 24 weeks. Phase B: Sitagliptin 100 mg once a day for 80 weeks. intervention 4: Phase A: Placebo matching Sitagliptin 200 mg once a day for 24 weeks. Phase B: Sitagliptin 200 mg once a day for 80 weeks. intervention 5: Phase A: Patients not meeting specific glycemic goals will receive open-label metformin as 500 mg, 850 mg, and 1000 mg oral tablets titrated at the discretion of the investigator. Phase B: These patients will not initiate Phase B double-blind medication.

Protocol document: