Type 1 Diabetes Extension Study

This is a multi-center, prospective, non-interventional study that focuses on the long- term effects following participation in selected ITN new-onset Type1 Diabetes Mellitus studies with immunomodulatory agents (T1DM, T1D). This observational study will: * follow participants to determine how long they continue to produce insulin, and * will also assess how changes in the immune system over time relate to the ability to produce insulin. This information could help design better therapies for type 1 diabetes in the future.

Inclusion Criteria: * Prior participant in an Immune Tolerance Network (ITN) executive committee approved T1DM study. * Ability to sign informed consent/assent (as applicable for children). Exclusion Criteria: * Any medical condition that in the opinion of the principal investigator would interfere with safe completion of the trial; or * Inability to comply with the study visit schedule and required assessments.