High performance liquid chromatography used to distinguish the autoimmune hypoglycemia syndrome from factitious hypoglycemia

Recurrent episodes of spontaneous hypoglycemia developed in a 30-yr-old woman who had received a brief course of insulin therapy 10 yr previously. She denied surreptitious insulin administration, and the autoimmune hypoglycemia syndrome was considered. Her insulin levels could not be reliably measured because of the presence of circulating antiinsulin antibodies, which interfere with standard RIA techniques. Reverse phase high performance liquid chromatographic analysis of serum obtained during a hypoglycemic episode revealed a mixture of beef and pork insulins but no human insulin, firmly establishing the diagnosis of factitious hypoglycemia. This case illustrates the value of reverse phase high performance liquid chromatography in characterizing patients in whom the autoimmune hypoglycemia syndrome is suspected.