New onset diabetic ketoacidosis in a renal transplant recipient.

Post-transplant diabetes mellitus (PTDM) is a well-known solid organ transplant complication, which can be related to immunosuppressants, particularly tacrolimus. We report an unusual presentation of PTDM with diabetic ketoacidosis (DKA). This is unique as PTDM typically resembles Type 2 DM, whereas DKA is associated with Type 1 DM and has rarely been reported as a complication of tacrolimus. A 38-year-old African American male on LCP-tacrolimus presented four months post kidney transplant with vomiting, weakness, poor appetite, and polyuria. Labs demonstrated hyperglycemia, ketonuria, and high anion gap metabolic acidosis. He was nonobese and had no personal or family history of Type 2 DM. DKA was suspected to be secondary to tacrolimus-induced pancreatic beta cell damage worsened by supratherapeutic tacrolimus levels. Latent autoimmune diabetes in adults (LADA) was diagnosed when further testing showed insulinopenia, low C-peptide, and anti-glutamic acid decarboxylase (GAD) autoantibodies. He required 120-units of subcutaneous insulin daily. Our literature review revealed only 16 other tacrolimus-induced DKA cases. No cases reported anti-GAD positivity and most showed beta cell toxicity reversibility with tacrolimus tapering or substitution. Our patient was early post-transplant with leukocytopenia, so tacrolimus was not exchanged. This unusual PTDM case may have resulted from both autoimmune and tacrolimus-induced beta cell destruction. Physicians should be aware of new onset LADA post-transplantation and tacrolimus toxicity leading to DKA, even in patients without traditional risk factors. Anti-GAD antibody screening in patients on tacrolimus who develop PTDM may identify patients less likely to recover beta cell function with immunosuppression augmentation which requires careful monitoring.