Inclusion Criteria  Diagnosis of T1D for a minimum of 5 years Stable, optimized diabetic regimen for at least 3 months prior to enrollment  Exclusion Criteria  Medical history of islet cell, kidney, and/or pancreas transplant Occurrence of 2 or more severe, unexplained hypoglycemic events within 6 months prior to enrollment Known causes of diabetes other than T1D Immunosuppressant therapy in the previous 30 days and/or requirements for chronic immunosuppressive therapy during the study Prior treatment with gene therapy or edited product