Insulin allergy in a patient with Type 2 diabetes successfully treated with continuous subcutaneous insulin infusion

Patients with poor control of Type 2 diabetes on maximum oral hypoglycaemic therapy invariably need insulin therapy. Insulin allergy is uncommon, particularly in patients with Type 2 diabetes. Management of the condition can be difficult, and here we report the case of a patient with Type 2 diabetes and insulin allergy successfully managed with a continuous subcutaneous insulin infusion (CSII).

A 60-year-old man was referred with insulin allergy. He had poorly controlled Type 2 diabetes (glycated haemoglobin 10.4%), on maximum doses of sulphonylurea and metformin, with osmotic symptoms. He was compliant with diet and tablets. His diabetes was complicated by retinopathy, nephropathy, coronary heart disease, obstructive sleep apnoea, obesity, depression and hypertension. He commenced on twice daily mixed insulin and, shortly after, developed pain, itching and erythema at the injection sites. The sites became indurated and tender, and he had constitutional symptoms. The insulin was changed to other preparations, including short- and long-acting analogues, with similar responses. Triple therapy with rosiglitazone was tried, with no improvement in control. Skin-prick testing confirmed allergy to insulin rather than additives. The patient was reluctant to undergo desensitization. He was commenced on an insulin pump in addition to his oral hypoglycaemics, and achieved fair control (glycated haemoglobin 8.3%) on 88 units of lispro per day, with little or no skin or systemic reaction.

This is the first case report of insulin allergy in Type 2 diabetes being successfully managed by CSII.