Although allergic reactions to insulin are uncommon, they can be difficult to diagnose and management may be very difficult in subjects with Type 1 diabetes with severe allergy. Access to allergists and specialist diagnostic tests is limited and few diabetes specialists are familiar with desensitization as a means of treating allergy. People with diabetes may develop symptoms which mimic insulin allergy but are attributable to other conditions.
Here we describe three cases of insulin allergy. One patient presented with severe, albeit localized, urticarial reactions at injection sites. The most severe case was a woman with recent-onset Type 1 diabetes who presented with grade 2 anaphylaxis. The third patient presented with generalized urticaria and angioedema. Insulin allergy was confirmed in all three cases.
Assessment involved measurement of immunoglobulin and anti-insulin antibody levels. Skin testing was performed in two cases. Treatments included desensitization in one case, alternative insulin preparations, antihistamines and continuous subcutaneous insulin infusion. In all three cases of insulin allergy there has been successful resolution of symptoms.
The clinical assessment and investigation in cases of suspected insulin allergy is described, along with detailed algorithms for skin testing and desensitization. This case series demonstrates an approach to challenging cases of suspected insulin allergy which will be helpful for diabetes specialists.