Combination Therapy With Sitagliptin and Lansoprazole to Restore Pancreatic Beta Cell Function in Recent-Onset Type 1 Diabetes

Inclusion Criteria: * Diagnosis of type 1 diabetes, based on American Diabetes Association criteria, recently diagnosed (within the 6 months before Screening) and confirmed by the presence of at least 1 diabetes related autoantibody (either glutamic acid decarboxylase \[GAD\], insulinoma-associated protein \[IA 2\], or insulin, the latter measured within 10 days after starting insulin therapy). * Male or female aged between 11 and 45 years, inclusive. * Able to swallow study capsules. * Willing to comply with "intensive diabetes management" as directed by the investigator, with the goal of maintaining blood glucose as close to American Diabetes Association recommendations as possible. * Willing to comply with the schedule of study visits and protocol requirements. Exclusion Criteria: * Use of a GLP 1R agonist or DPP 4 inhibitor within 1 month before enrollment. * Use of a PPI within 1 month before enrollment. * Use of an oral hypoglycemic agent within 1 month before enrollment or use of thiazolidinediones within 3 months before enrollment (although thiazolidinediones may be used \<7days before enrollment). * Females of childbearing potential who are unwilling or unable to use an acceptable method to avoid pregnancy for the entire study period. * Females who are pregnant or breastfeeding at the time of enrollment. * Subjects with any of the following conditions: * Renal insufficiency, defined as estimated glomerular filtration rate (GFR) less than 50 mL/min at Screening, calculated using the Modification of Diet in Renal Disease (MDRD) equation. * History of a serious hypersensitivity reaction to sitagliptin or lansoprazole, such as anaphylaxis or angioedema. * Severe hepatic insufficiency. * History of pancreatitis or gallbladder disease * Any significant medical condition, which in the opinion of the investigator or medical monitor would interfere with study participation.