Insulin antibodies are well described, though with a decreased prevalence in recent years, following the introduction of human insulins. We report a case of Type 1 Diabetes Mellitus (T1DM) complicated by frequent hypoglycaemic and ketotic episodes requiring immunosuppressive treatment and regular plasma exchange. 

This 42 year old lady was diagnosed with T1DM in 1995 with good glycaemic control initially. However she developed local reactions at the site of insulin injection soon, followed by worsening glycaemic control over the next two years requiring multiple hospital admissions for Diabetic ketoacidosis and hypoglycaemia. She received corticosteroids for presumed Type III hypersensitivity reaction to intra-venous insulin which improved glycaemic control transiently. However erratic control continued despite commencement of insulin pump (CSII) therapy. She required highly variable and large insulin doses causing high glucose levels and hypoglycaemia, very unpredictably. Her insulin antibodies returned positive. She subsequently had islet cell transplantation and two whole pancreas transplantation, all of which failed. She was then commenced on mycophenolate and intermittent pulse corticosteroids with improving glycaemic control. Again as this failed to maintain, she was trialled on plasma exchange (PE) with good effect. Subsequently,  maintenance PE every two weeks and adjuvant Rituximab has resulted in infrequent hospitalization and better glycaemic control. She has autonomic neuropathy and hypoglycaemia unawareness, which is managed with continuous glucose monitoring and CSII.

 The local allergic response to insulin was probably the sensitising event leading to the development of anti-insulin antibodies. Recognition and immune-modulation of insulin antibodies has resulted in better glycaemic control.

 Discussion point: Management of brittle glycaemic control due to insulin antibodies with immune modulation.