Severe autoimmune hypoglycemia with insulin antibodies necessitating plasmapheresis

To report a case of autoimmune hypoglycemia.

We describe the clinical course of a patient with autoimmune hypoglycemia, including results of biochemical and histocompatibility antigen studies, as well as the therapeutic intervention and follow-up.

A 77-year-old man presented with clinical manifestations of severe spontaneous hypoglycemia associated with extremely high levels of insulin (>300 mU/mL) and insulin antibodies (>100 U/mL) without any exogenous insulin administration. He had no other associated autoimmune disorder or exposure to the sulfhydryl group of drugs. Corticosteroid therapy was initiated, but the patient continued to have hypoglycemia and required plasmapheresis. The hypoglycemia resolved after plasmapheresis. During follow-up, the patient was treated with prednisone, the dose of which was tapered gradually. The insulin antibodies, which had decreased rapidly after plasmapheresis, gradually disappeared within a few months. The patient remained free of hypoglycemia as well as insulin antibodies 11 months after corticosteroid therapy was discontinued.

Although autoimmune hypoglycemia is an uncommon disorder, it should be considered in any patient with hypoglycemia in the setting of nonsuppressed insulin levels associated with insulin antibodies.