A Longitudinal, Observational Study Comparing Real-World Experiences of Teplizumab-Treated and Untreated Participants With Stage 2 Type 1 Diabetes in the United States

This study is an observational, longitudinal, non-interventional real-world study in the United States. The study is meant to describe the experience of participants with a history of stage 2 type 1 diabetes who have been infused with teplizumab and the experience of participants with stage 2 type 1 diabetes who have not been infused with teplizumab, and to compare descriptively the experiences of the two groups. Primary Objective: \- To characterize health related quality of life, diabetes-related anxiety, diabetes-related burden, and ease of diabetes management, and how participants feel, form and function in those who infused and those who did not infuse with teplizumab Secondary Objectives: * To show the clinical transitions experienced by those who infused and those who did not infuse with teplizumab * To describe the prevalence and timing of diabetes misclassification and the temporal patterns between misclassification, antibody testing, and the correct diagnosis of type 1 diabetes in those who infused and those who did not infuse with teplizumab * To estimate the impact of diagnostic misclassification on the timing of progression to stage 3 type 1 diabetes in those who infused and those who did not infuse with teplizumab * To characterize glucose monitoring strategies in those who infused and those who did not infuse with teplizumab where possible * To characterize insulin use in those who infused and those who did not infuse with teplizumab where possible * To characterize longitudinal health care resource utilization in those who infused and those who did not infuse with teplizumab