Endocrine Abstracts

Introduction: Insulin allergy is a clinical challenge in the management of type 1 diabetes mellitus since there is no other therapeutic alternative. The specific cause of insulin allergy can be related to insulin itself or to additives including zinc, protamine and meta-cresol. The manifestations range from localized reactions to systemic severe anaphylaxis. We here present the case of a generalized allergy to insulin excipient meta-cresol, in a type 1 diabetic patient successfully handled by desensitization therapy.

Case-presentation: A 35 years old female with a medical history of seasonal allergic sinusitis and type 1 diabetes mellitus for 4 years on insulin glargine and insulin aspart, presented to our department for the development of generalized urticaria, erythema and pruritus. Symptoms started since diabetes diagnosis, but the intensity and frequency of these reactions increased recently. Symptoms occur 10-30 minutes after insulin injection. Antihistamine treatment improves partially the condition. The allergic reaction persisted with the other types of insulin (regular human insulin, NPH-insulin, detemir, glulisine). Immunological evaluations revealed negative results for specific immunoglobulin E to latex and protamine. Anti-human insulin IgE antibodies (CAP) were inferior to 0,1 kU/l. Skin prick testing revealed a hypersensitivity to the all types of insulins stated above. Because the patient had an allergic reaction to all available insulin and meta-cresol was the only excipient common to all tested insulin types, a presumed allergy to the excipient meta-cresol was diagnosed. We started desensitization therapy to glargine following Joselyn Rojas’s protocol using subcutaneous insulin injection with simultaneous intravenous regular insulin infusion associated to premedication with corticosteroid and H1 antagonist. Subsequently, we conducted desensitization to aspart insulin adopting Füsun Erdenen’s protocol. Seen 1 month later, the patient didn’t require antihistamines anymore with tremendous allergic symptoms relief.

Conclusion: Allergy to insulin excipient meta-cresol in a type 1 diabetic is unusual and represents a substantial challenge warranting a stepwise approach to be diagnosed and managed. Specific immunotherapy should be considered as a key treatment option.