A Case of Skin, and Secondarily Generalized, Reaction to Insulin Injection.

PRESENTATION R.J. is a 51-year-old man who has had type 2 diabetes for 18 years. Because of poor metabolic control with oral agents, he was prescribed a premixed formulation of regular and NPH insulin (Novo Nordisk, Madrid, Spain). Two weeks later, he developed pruritic lesions at the injection site. As treatment continued, lesions of similar characteristics developed in previous injection sites. He was switched to a different brand of the same mixture of insulins (Eli Lilly, Madrid, Spain). He presented to the emergency department when, after injecting a dose of insulin, he developed nausea, labial edema, shortness of breath, and urticaria lesions progressing from trunk to extremities. He improved rapidly with oral antihistamines and intravenous corticosteroids. R.J. was then evaluated by the Allergology Department and was diagnosed with having experienced an anaphylactic reaction. Three days later, blood samples were taken for laboratory testing (Table 1). Skin prick and intradermal tests revealed sensitization to all insulins tested: regular, NPH, and premixed formulations (Novo Nordisk and Eli Lilly), as well as lispro, aspart, glulisine, glargine, detemir, aspart/ aspart protamine, and lispro/lispro protamine. Results were considered positive when the diameter of the wheal was ≥ 3 mm larger than the negative control. Saline solution and histamine were used as negative and positive controls, respectively. Tests against other potential allergens were not deemed necessary because he showed reaction to all the preparations tested, which had different excipients. A diagnosis of type I hypersensitivity to insulin was established. R.J. underwent a rapid subcutaneous desensitization to the initial mixture of insulins (regular and NPH [Novo Nordisk]) uneventfully, tolerating increasing concentrations of the preparation to a maximum dose of 18 units. He was discharged with a prescription for this mixture, 22 units before breakfast and 16 units before dinner. Eight months later, he had had two mild generalized reactions that were controlled with oral antihistamines.