Abstract
IntroductionInsulin allergy may occur in patients treated with subcutaneous applications of insulin preparations. Besides additives in the insulin preparation such as protamine, cresol, and phenol, the insulin molecule itself may be the cause of the allergy. In the latter case, therapeutic options are rare.Case presentationA 68-year-old man with poorly controlled type 2 diabetes mellitus received different insulin preparations subcutaneously while on oral medication. Six to eight hours after each subcutaneous application, he developed pruritic plaques with a diameter of >15 cm at the injection sites that persisted for several days. Allergologic testing revealed positive reactions against every insulin preparation and against protamine. Investigation of serum samples demonstrated IgG antibodies against human and porcine insulin. We treated the patient with human insulin using an ultra-rush protocol beginning with 0.004 IU and a rapid augmentation in dose up to 5 IU. Therapy was accompanied by antihistamine therapy. Subsequent conversion to therapy with glargine insulin (6 IE twice daily) was well-tolerated.ConclusionAs reported in this case, desensitization with subcutaneously administered human insulin using an ultra-rush protocol in patients with an insulin allergy may present an easy form of therapy that is successful within a few days.
Highlights
Insulin allergy may occur in patients treated with subcutaneous applications of insulin preparations
As reported in this case, desensitization with subcutaneously administered human insulin using an ultra-rush protocol in patients with an insulin allergy may present an easy form of therapy that is successful within a few days
Systemic, potentially life-threatening reactions such as urticaria or anaphylaxis have been reported [1]. Both types of hypersensitivity may result from the insulin molecule itself, and from protamine, which is used in many preparations to delay insulin absorption [3,4,5]
Summary
In the past, when unpurified insulins were used, allergic reactions to the drug were reported in 10% to 56% of patients [1]. In patients with diabetes mellitus, subcutaneous administration of protamine-containing insulin preparations can provoke delayed, T-cell mediated skin reactions or granulomatous hypersensitivity [6]. Therapy On day 1, we treated the patient with subcutaneous injections of human insulin Protamine-containing test solutions (6 and 7) showed clear positive results 20 minutes after injections, while other components were negative. Up to the present time, the patient has tolerated this form of therapy and fexofenadin treatment was reduced to 180 mg daily, and stopped completely, 6 months after desensitization
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