Endocrine Abstracts

Patients with type 1 diabetes (T1DM) and insulin hypersensitivity reaction of any type are at high risk of acute and chronic long term complications of hyperglycaemia and glycaemic variability. Such patients are challenging to manage. We present a case report. A 57 year old lady with T1DM for 21 years managed with insulin pump for 7 years reported new onset intermittent skin reaction at the pump infusion site over the last two years. She described her skin becoming swollen and hard and sometimes itchy and red within 4–12 hours of starting NovoRapid insulin via a new cannula. The reaction persisted up to a week and swelling subsided without any intervention. The reaction continued with the new types of cannula or with Humalog or Apidra in the pump. The reaction also happened with subcutaneous injections of quick, intermediate and long acting insulin. The reactions seemed to be more pronounced during infections. Skin prick and intradermal testing to all human, bovine and porcine insulins were negative. Specific IgE to insulins were negative and mast cell tryptase was normal. She was diagnosed to have type 3 hypersensitivity reaction to insulin molecule. Antihistamines would help minimise itching but no other treatments were deemed suitable as reactions were intermittent and satisfactory glycaemic control was maintained. She will be considered for trial of DiaPort, peritoneal insulin delivery system in future if reactions become more persistent and/or glycaemic control is affected. Insulin hypersensitivity presents a management challenge for patients with insulin dependent diabetes. Its incidence has reduced since the invention of human insulin. Most common type is immediate or less commonly biphasic IgE medicated type 1 local or systemic reaction. Type 3 hypersensitivity is less common and usually presents with a slightly delayed local reaction. Management of hypersensitivity reactions involves switching to different insulin, antihistamines, glucocorticoids or desensitisation although type 3 hypersensitivity is more difficult to treat. It is important to note that the hypersensitivity could either be due to insulin itself or other substances in the insulin injections therefore it is critical to recognise the exact allergen. DiaPort system of insulin delivery through peritoneum is a promising option for such patients if other treatments fail or are deemed unsuitable.