Systemic allergy to endogenous insulin during therapy with recombinant DNA (rDNA) insulin

Clinically significant allergic reactions with insulin therapy are known to occur. There have been rare reports of allergic reactions to endogenously secreted insulin manifested as insulin resistance. No reports of systemic or local allergic reactions to endogenous insulin have previously been cited, and no immunologic reactions to endogenous insulin have been reported during therapy with recombinant (rDNA) insulin.

We report a case in which the patient, a 28-year-old black woman who initially presented with gestational onset diabetes but postpartum continued to require insulin, developed generalized allergic reactions during therapy with subcutaneously injected rDNA insulin. Similar reactions occurred with sulfonylurea therapy. She was unable to tolerate any pharmacologic therapy for diabetes without concurrent use of at least 10 mg of prednisone per day.

Skin testing with the insulin preparations were positive, while skin testing to the sulfonylurea hypoglycemic agents were negative. IgE antibodies to insulin where present in high titer. Oral challenge to sulfonylurea hypoglycemic agents produced generalized urticarial reactions coinciding with time of peak insulin secretion. Oral challenge to other medications containing sulfa produced no adverse reaction. Biphasic hypersensitivity reactions occurred during attempts at desensitization which were futile without simultaneous glucocorticoid therapy.

This is the first report of local and systemic allergic reactions to endogenously secreted insulin in association with rDNA insulin therapy. Although immunologic complications with rDNA therapy appear less frequently than with insulin preparations, this case illustrates the need for continued awareness for potential allergic complications occurring with rDNA insulin therapy.