Type 1 diabetes mellitus after cord blood transplantation from an unrelated donor with a disease‐sensitive haplotype

ABSTRACT Allogeneic hematopoietic stem cell transplantation (allo‐HSCT), a curative treatment for hematopoietic neoplasms, often causes various autoimmune disease‐like conditions. In contrast, allo‐HSCT‐related type 1 diabetes mellitus is extremely rare. Herein, we report a case of allo‐HSCT‐related type 1 diabetes mellitus in a patient who had undergone cord blood transplantation (CBT) as a treatment for acute myeloid leukemia. The patient's human leukocyte antigen was replaced with the donor type after transplantation. The donor had a disease‐sensitive haplotype. To the best of our knowledge, this is the first reported case of type 1 diabetes mellitus following CBT.