Is MK0431A (fixed-dose combination tablet of sitagliptin and metformin) more effective and safer to achieve glycemic control for the treatment of T2DM in patients aged 10-17 who are on metformin monotherapy or in combination with insulin) and does the addition of sitagliptin reduce hemoglobin A1c (A1C) more than the addition of placebo after 20 weeks of treatment?

MK-0431A-170-04
Drug: Metformin Drug: Sitagliptin + Metformin FDC Drug: Placebo to Metformin Drug: Placebo to Sitagliptin + Metformin FDC Biological: Insulin Biological: Insulin glargine

MK-0431A (sitagliptin/metformin: 50/500, 50/850, and 50/1000 mg), metformin (500, 850, and 1000 mg), and their matching placebos will be supplied as oral tablets.

During the 1-week single-blind placebo run-in period, patients will receive the following treatments: • one tablet of metformin (500 mg; 850 mg; or 1000 mg) and one tablet of MK-0431A placebo (matching the metformin dose), administered twice daily prior to the morning ane evening meals. During the 20-week double-blind treatment period, patients will receive one of the following treatments: • one tablet of MK-0431A and one tablet of metformin-placebo, administered twice daily prior to the morning and evening meals. one tablet MK-0431A-placebo and one tablet of metformin, administered twicedaily prior to the morning and evening meals. Open-label insulin (for background or rescue therapy) will be sourced locally and administered subcutaneously based on instructions provided by the Investigator (based on accepted local, national or international guidelines for the indication and use of insulin). Dose of background insulin should remain stable (of any type, variance in dose to be ?15% of total daily dose) for the duration of the trial

MK-0431A-170-05

Open-label insulin (background or rescue therapy) taken during the base study and insulin glargine initiated in the extension study will be sourced locally, and administered subcutaneously based on instructions provided by the Investigator (based on accepted local, national or international guidelines for the indication and use of insulin).

Patients in this study will remain on their randomized double-blind study medication assigned in the base study (if not on background insulin or rescued with insulin in the base study) that is deemed clinically inappropriate by the investigator if their glycemic values meet protocol-specified thresholds.

1. Subjects between the age of 10 to 17 years on day of signing informed consent with randomization to occur prior to 18th birthday.
2. Diagnosed Type 2 Diabetes Mellitus (T2DM)
3. Patient on metformin monotherapy (?1500 mg/day, for ?12 weeks) with A1C ?6.5% and ?10.0% OR Patients is on stable doses of metformin (?1500 mg/day, for ?12 weeks) and insulin (of any type, variance in dose to be ?15% of total daily dose for ?12 weeks prior to Screening Visit/ Visit 1) with an A1C?7.0% and 10%.
4. HbA1C greater than or equal to 6.5% and less than or equal to 10.0% on metformin, greater than or equal to 1500 mg/day, for greater than or equal to 12 weeks. (Participants on a daily dose of metformin greater than or equal to 1000 mg/day, but less than 1500 mg/day may be eligible if there is documentation that higher doses are not tolerated).
5. Participant has a family member or adult closely involved in the daily activities.

Additional clarity given through Specific Treatments:
1.Patient has previously taken a DPP-4 inhibitor (such as sitagliptin, vildagliptin, alogliptin, or saxagliptin) or GLP-1 receptor agonist (such as exenatide or liraglutide). Note: Patients who have participated in single-dose studies with these agents at least 12 weeks prior to screening are eligible to participate.

2. Patient has initiated chronic treatment with a medication known to cause:
a. weight gain within 30 days of Visit 1 or b. weight loss (such as orlistat) or c. increase blood glucose within 8 weeks of Visit 1.
Note: Patients on a weight loss program and not in the maintenance phase, or who have undergone bariatric surgery within 12 months prior to signing the informed consent will be excluded.
Note: Patients who have been treated with an anti-psychotic agent within the past 12 weeks will be excluded.

3. Patient is currently participating in or has participated in another study with an investigational compound or device within the prior 12 weeks of signing the informed consent (including patients who have participated in single-dose studies with these agents) and does not agree to refrain from participating in any other study while participating in this study.
Note: A patient who has participated in a non-interventional or placebo study may be enrolled.

4. Patient is on or likely to require treatment with ?14 consecutive days or repeated courses of pharmacologic doses of corticosteroids. Note: Inhaled, nasal, and topical corticosteroids are permitted.

5. Patient has undergone a surgical procedure within the prior 4 weeks or has major surgery planned during the study. Note: Patients who have undergone minor surgery within the prior 4 weeks and are fully recovered or patients who have planned minor surgery may participate. Minor surgery is defined as a surgical procedure involving local anesthesia.