Insulin Absorption in a Patient with Local Subcutaneous Amyloid Deposition

Abstract

The patient was a 91-year-old male who was diagnosed with type 2 diabetes at 60 years of age, and started insulin treatment at 78 years of age. His HbA1c was 10.6 % (NGSP value) at the first visit to the hospital, despite the administration of 61 units of insulin. An abdominal examination revealed elastic-hard masses at the insulin injection sites in his abdomen. The patient was admitted for further examination. T1- and T2-weighted MRI images showed low intensity masses with no signal inhibition on fat-suppressed images. His skin biopsy samples were pale with an eosinophilic nonstructural substance stained orange with Congo-Red. The lesions were thus diagnosed as insulin injection-induced local amyloid deposition. The required insulin dose was markedly decreased after changing the insulin injection sites. In addition, the blood insulin levels were markedly lower when insulin was injected into the amyloid-deposited region than into healthy skin, thus indicating markedly reduced insulin absorption from the region containing amyloid. The first case of reduced insulin absorption due to insulin injection-induced local amyloid deposition reported as a possible cause of poor blood glucose control.