Rapid Desensitization with Intravenous Insulin in a Patient with Diabetic Ketoacidosis and Insulin Allergy

ABSTRACT Objective We report a case of insulin desensitization in a patient with known allergy to multiple insulin preparations who presented with diabetic ketoacidosis (DKA). Methods Clinical and laboratory data, and desensitization protocols are presented. Results A 65-year-old woman with type 2 diabetes and a documented insulin allergy presented with severe DKA. She was managed initially with intravenous (IV) fluids, sodium bicarbonate, and hemodialysis. An intradermal skin test was positive for 0.01 units/mL of human regular insulin. A rapid desensitization protocol for IV human regular insulin was initiated after pretreatment with methylprednisolone, ranitidine, montelukast, and cetirizine. An initial dilution of 1 unit of insulin in 100,000 mL of 0.9% sodium chloride was started at 5 mL/hour IV. The dilution was increased at 60-minute intervals to 1 unit/10,000 mL, 1 unit/1,000 mL, 1 unit/100 mL, 1 unit/10 mL, then 1 unit/1 mL. The dose was then increased from 1 to 7 units/hour (0.1 units/kg body weight/hour). The anion gap closed after 24 hours, and overlapping desensitization was started for subcutaneous (SC) human regular insulin starting with 0.00001 units with a gradual increase to 7 units before meals and 6 units at bedtime over 5 days. There were no anaphylactic reactions to IV or SC insulin. She was discharged with human regular insulin SC 4 times daily, oral montelukast, cetirizine, diphenhydramine as needed, and an epinephrine pen. No allergic reactions were reported at follow-up visits. Conclusion Rapid insulin desensitization is possible to allow treatment of DKA with human regular insulin IV in patients with known insulin allergy.