The review analyzes the current biomarkers used in monitoring pancreas transplant, from the simple and time-tested, to more sophisticated, including markers of allo- and autoimmunity, that are likely to play a larger role in future studies.Evaluation of alloimmunity includes serum levels of donor-specific antibody, and, ultimately, pancreas transplant biopsies with C4d staining. Our center has focused on markers of autoimmunity, including assessment of autoantibodies and autoreactive T cells. We have found that conversion of autoantibodies (including GAD65, IA-2, and ZnT8), or the development of a new positive autoantibody, particularly ZnT8, are associated with type 1 diabetes (T1D) recurrence in the pancreas transplant. Autoreactive T cells have also been identified in the peripheral blood, pancreas transplant and peripancreas transplant-lymph nodes, that have the potential to mediate human β/islet cell destruction in vivo.The monitoring of pancreas transplant biomarkers, particularly those associated with autoimmunity, has led to new insights into the pathogenesis of T1D. Progress in the elucidation of mechanisms of autoimmunity may lead to novel therapeutic approaches to both T1D recurrence of the pancreas transplant and perhaps also new onset T1D.