[Chronic insulin urticaria. Therapeutic efficacy and good tolerability of human insulins].

A case of type III (Arthus') hypersensitivity to insulin which occurred several years after insulin treatment was instituted is described. Its persistence even with highly purified insulins of bovine or porcine origin was suggestive of a direct reaction against insulin itself. The patient had no history of allergy and, contrary to most similar cases published, had not received intermittent insulin therapy. Using stimulation of lymphocyte blastogenesis, the authors were able to demonstrate the presence of specific antigen-mediated hypersensitivity to all insulins tested, including human insulins. The circulating immune complexes did not appear to be pathogenic, since the patient only had minimal retinopathy after 22 years of insulin-dependent diabetes. Human insulin was tolerated and proved effective in controlling both blood glucose levels and skin rashes in response to conventional insulins.