*Purpose: Demonstrate the outcomes of treatment with rituximab in patients with autoimmune diabetes after pancreas transplant.

*Methods: We present the treatment response to rituximab in 3 simultaneous pancreas and kidney transplant (SPK) patients who developed autoantibodies and hyperglycemia. All the patients received induction with anti-thymocyte globulin 6 mg/kg, maintenance immunosuppression with tacrolimus (Tac), mycophenolate (MPA) and prednisone (P). Patient 2 had MPA discontinued due to significant GI side effects. Amylase and lipase levels were normal and there were no new donor specific antibodies (DSA). A clinical diagnosis (hyperglycemia and de novo autoantibodies) of autoimmune diabetes was made in all cases as biopsies were contraindicated. Treatment consisted of high dose IV methyl prednisolone (total of 1-1.5gm over course of 3 days) with oral prednisone taper and 2 doses of rituximab 375mg/m² on day 0 and 15.

*Results: Patients 1 and 2 had a transient response to rituximab with improvement in their blood glucose levels. Over the course of 4-6 months after rituximab they developed worsening hyperglycemia and required insulin. Patient 3 improved and did not require insulin. All the patients had stable exocrine pancreas and stable renal allograft function. 1/3 patients responded to 2 doses of rituximab with improvement in their blood glucose levels and long term insulin free survival.

*Conclusions: Recurrent autoimmune diabetes after pancreas transplant is a less well recognized cause of pancreas allograft loss. Onset can be delayed and could occur despite appropriate levels of immunosuppression. Pancreatic autoantibodies that are frequently checked include anti-insulin, anti-islet cell, and anti-glutamic acid decarboxylase (GAD). The impact of this condition on long-term pancreas graft survival is unknown and optimal therapy is unknown. Further studies are required to determine the optimal dose and duration of rituximab, which could be a potential treatment option for such patients.

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