TrialNet Pathway to Prevention of T1D

Detailed Description: The Pathway to Prevention Study is conducted in two parts: * Screening * Monitoring (annual and semi-annual depending on risk) In Screening , a simple blood test is done to screen for the presence of diabetes-related biochemical autoantibodies (GAD and mIAA). Additional autoantibodies ICA, IA-2A, and ZnT8A will also measured in individuals positive for mIAA. ICA, IA-2A, and ZnT8A will be measured in individuals positive for GAD. Participants can go to a TrialNet Clinical Center, Affiliate, or request a screening kit to have their blood drawn by a local physician or laboratory. Participants will be provided with their screening results within 4-6 weeks. If autoantibodies are present, participants will be invited to have additional testing to determine their average risk of developing diabetes over the next 5 years. Participants that are single autoantibody positive will be re-tested annually for the development of multiple autoantibodies. Multiple autoantibody positive participants will undergo an eligibility visit which will include an Oral Glucose Tolerance Test (OGTT), re-testing for biochemical and islet cell autoantibodies if needed, and measurement of HbA1c. Multiple autoantibody positive individuals with a normal glucose tolerance and an HbA1c \< 6.0% will be asked to come for follow-up on annual basis; multiple autoantibody positive individuals with an abnormal glucose tolerance or an HbA1c ≥ 6.0%will be asked to come for follow-up visits on semi-annual basis. Participants will be monitored for possible progression towards type 1 diabetes and may be offered the opportunity to enter into a prevention study such (e.g., Oral Insulin prevention study) or an early treatment study if they are diagnosed with type 1 diabetes while participating in the Natural History Study.