THU278 Hidden In The Immune System: Exogenous Insulin Antibody Syndrome In A Patient With Latent Autoimmune Diabetes In Adults

Disclosure: H.L. King: None. R. Nagappan: None. A. Sliwinska: None. Hidden in the Immune System: Exogenous Insulin Antibody Syndrome in a Patient with Latent Autoimmune Diabetes in Adults Background: Exogenous insulin antibody syndrome (EIAS) is a rare syndrome associated with insulin antibodies induced by exogenous insulin, found predominantly in patients with type 2 diabetes using various insulin formulations. Here, we present a case of young man previously diagnosed with type 2 diabetes, who was found to have severe refractory diabetic ketoacidosis (DKA) due to EIAS. Clinical Case: A 46-year-old man with a history of type 2 diabetes presented to an outside hospital for one week of fever and malaise. Laboratory studies were notable for serum glucose of 600 mg/dL (70-90mg/dL), HCO3 3 mmol/L (22-28mmol/L), and creatinine of 3.9 mg/dL (0.7-1.3mg/dL). He was diagnosed with DKA, shock and renal failure. During hospital stay, he remained on an insulin drip due to multiple unsuccessful attempts of transitioning to subcutaneous insulin, requiring over 1000 Units of insulin daily. This prompted insulin antibody testing that resulted elevated at >50U/mL (0-0.4U/mL), concerning for EIAS. Treatment was initiated with 5 days of IVIG and mycophenolate mofetil. During this treatment, his baseline insulin infusion rate of 30 Units/hr declined to 18 Units/hr, however at day 3, insulin requirements again increased. For better evaluation, quantitative insulin antibody values were requested and resulted as 362.5U/mL, followed by 350.9U/mL post IVIG treatment. After no significant improvement, patient was transferred to our hospital for further management of EIAS. Plasmapheresis was initiated followed by rituximab with plans for long term maintenance therapy. Dexamethasone was trialed but shortly after discontinued due concern of increased insulin resistance and hyperglycemia. Metformin was also started but discontinued due to concern of worsening acidosis in the setting of acute renal failure requiring CRRT. Ultimately, the patient was transitioned to subcutaneous U500 BID 75-150 Units based on scale. At discharge, metformin and pioglitazone were started. Due to the history of early onset insulin-dependent diabetes at age 30, he was tested for GAD-65 which resulted as positive at 0.28 nmol/L (<=0.02 nmol/L) and C peptide of 0.9ng/mL (0.8 - 3.9 ng/mL) consistent with LADA. Conclusion: EIAS is a rare and very challenging entity, increasing risks of severe ketoacidosis, hypoglycemic episodes and numerous other complications. Although mostly reported in type 2 diabetes, EIAS can occur in patients with LADA suggesting that autoimmunity may play a role. There is no FDA approved treatment, however attempts focus on eliminating antibodies by plasmapheresis, IVIG and immunotherapeutic agents. Presentation: Thursday, June 15, 2023