Assessment of a Case of Immediate-Type Allergy against Human Insulin in a Type 2 Diabetic Patient and Allergic Reactions to Human Insulin in Japan

We report a 64-year-old female patient with an insulin allergy. She was treated with a combination of oral antihistamines, topical hydrocortisone cream, and moisturizing agents, which resulted in the improvement of eczema and intense pruritus. To evaluate insulin allergy, intradermal skin tests were performed with several insulin agents for clinical use and 0.9% NaCl. Skin testing with semisynthetic human insulin resulted in local, immediate skin reactions such as itchy erythema and wheals. Furthermore, we analyzed our case and 25 Japanese cases of insulin allergy previously reported in the literature as far as we know. Interestingly, the number of male patients was approximately two times higher than that of female, and the insulin-specific IgE antibody test was positive in 21 patients. We should keep the possibility of human insulin allergy in mind and prepare for it when initiating human insulin therapy.