Delayed-type hypersensitivity reaction to the meta-cresol component of insulin

Reactions to recombinant human insulin preparations occur at a rate of 2.4%. Although most have been traced to immunological reactions to the insulin, recent reports suggest that some adverse reactions can occur to the nonmedicinal excipients or preservatives of commercially available insulin preparations.

To investigate a localized delayed cutaneous reaction to human insulin.

Intradermal and patch testing were performed on a patient to evaluate sensitivity to commercial human insulins, meta-cresol, and other sensitizers.

Patch test results were positive to the meta-cresol preservative.

This is the first report, to our knowledge, of a reaction to meta-cresol in commercial preparations of insulin. This reaction should be considered in the differential diagnosis of adverse reactions to insulin injections.