A Case of Possible Hypersensitivity Reactions to Human Insulin

Background: Insulin therapy is commonly used in diabetic patients. It represents the only option for patients with type 1 diabetes mellitus and could be part of the treatment plan for the patient with type 2 diabetes mellitus. Clinical appearance of hypersensitivity reactions to insulin vary significantly, depending on the immune mechanism involved. Many skin prick tests could be interpreted as positive reactions (either by using inappropriate concentrations or due to other mast cell degranulation causes).Case History: Four weeks after initiation of insulin therapy, patient V.I. experienced a maculopapular rash, severe pruritus, induration at the injection site after 12-24 hours after administration. The presence of an insulin sensitization was proven by skin prick test and determination of specific IgE.Discussions: Patients suspected of insulin hypersensitivity should be evaluated by an allergologist in order to obtain a correct diagnosis and to identify other possible causes for the insulin intolerance. Desensitization should be undertaken only in real insulin hypersensitivity cases in patients who need it.Conclusions: Insulin allergy can be managed successfully with a good cooperation between the diabetologist and the allergologist.