The Prospective Observational Study of TPIAT (POST) study is an 11-center registry study of persons who undergo total pancreatectomy with islet auto-transplantation (TPIAT) and are followed for at least a year after surgery. The study's first aim is to determine systematically how patient and disease characteristics are associated with favorable pain and health-related quality-of-life outcomes (HRQOL) after TPIAT, the optimal timing of the TPIAT intervention to resolve pain and improve HRQOL, and in a subset of patients, the impact of central sensitization on pain resolution. The second aim is to determine how patient and disease characteristics are associated with favorable glycemic outcomes from the IAT procedure and the optimal timing of TPIAT to obtain postsurgical insulin independence. The final aim is to determine the cost-effectiveness of TPIAT compared to continued medical and surgical management. Enrollment began in January 2017 with planned enrollment of 450 participants.