A Pilot Study to Assess the Glucose Lowering Effect of Metformin and Sitagliptin in Adolescents With Type 1 Diabetes

* The study will include a total of 4 visits. The time period between the very first visit and the very last visit will be between 10 and 15 weeks. Each participant will be randomized to one of the 3 groups in the study. The groups are as follows: * Group 1: Insulin and sitagliptin * Group 2: Insulin and metformin * Group 3: Insulin and combination of sitagliptin and metformin * The study is a randomized open label design. All subjects will undergo a screening visit; if inclusion and exclusion criteria are fulfilled they will be enrolled in the study. At the time of enrollment the subject will continue their home insulin regimen and will be randomized to an add an oral hypoglycemic agent(s) : metformin, sitagliptin or combination therapy (metformin and sitagliptin). The total duration on study medication will be 6 weeks. All subjects will undergo a baseline mixed meal tolerance test (MMTT) in their standard or usual insulin Each subject will undergo a total of two studies. Blood draws will be necessary.