Exogenous Insulin Antibody Syndrome in a Pediatric Patient: Successful Treatment with Mycophenolate Mofetil.

INTRODUCTION: Exogenous insulin antibody syndrome (EIAS) rarely occurs in type 1 diabetes and should be considered in those with blood glucose levels outside the target range requiring greater than 2 units/kg/day of insulin without obesity. We describe the novel treatment of this condition using mycophenolate mofetil monotherapy in a pediatric patient in the outpatient setting.

CASE PRESENTATION: A 17-year-old Caucasian male with type 1 diabetes experienced an abrupt increase in insulin requirements from 1.7 to 3.3 units/kg/day. Total insulin level was 7 µIU/mL with free insulin of 4.8 µIU/mL (68% of the total insulin), suggesting the presence of insulin antibodies. Switching from insulin aspart to glulisine was unsuccessful as insulin requirements increased to 4.4 units/kg/day. Treatment with oral mycophenolate mofetil decreased insulin requirements to 1.4 units/kg/day after 7 months. Total and free insulin levels improved to 5.2 and 4.6 µIU/mL, respectively (free insulin was 88% of total insulin). No adverse effects were encountered.

CONCLUSION: Mycophenolate mofetil monotherapy is successful in safely treating EIAS in a pediatric patient.