Severe insulin allergy after percutaneous transluminal coronary angioplasty

Background: Insulin therapy is essential for type 1 and inadequately controlled type 2 diabetic patients. Insulin allergies have become less common since the introduction of highly purified human recombinant insulin. There are rare reports of severe insulin allergic reactions after percutaneous transluminal coronary angioplasty (PTCA) in patients with type 2 diabetes who had no previous allergic reactions. To better understand the causes and presentation of this rare acute reaction, we present the following observed case. Case summary: A 63-year-old Chinese man (height, 172 cm; weight, 68.5 kg) with a 17-year history of type 2 diabetes and hypertension was first admitted to the West China Hospital, Sichuan University, Sichuan, People's Republic of China, for uncontrolled type 2 diabetes. He used regular human insulin, neutral protamine Hagedorn insulin, or premixed insulin without any allergic reactions. Four months later, PTCA was performed because of an acute myocardial infarction. The patient was administered 50 mg of protamine after active abdominal bleeding due to a right external iliac artery rupture. Three months later, recurrent raised, pruritic erythema occurred at the insulin injection site immediately after injection. Four weeks later, he experienced an attack of generalized urticaria at multiple previous injection sites (abdomen, upper arms, thighs) after injecting premixed insulin. It was accompanied by dizziness and palpitations. During the following 3 months, the symptoms recurred 3 times; one time, the patient reported losing consciousness for 2 to 3 minutes. The results of a skin prick test found that he was allergic to human recombinant insulin and insulin lispro. The allergy was resolved by changing his treatment regimen from insulin to oral hypoglycemic agents. A Naranjo score of 10 suggested a definite relationship (score ≥9) between the adverse drug reaction and the insulin administration. Conclusions: We present a definite case of allergy associated with insulin and insulin lispro administration. The patient had not experienced anaphylactic reactions prior to PTCA and protamine administration.