Hypoglycemia due to surreptitious injection of insulin: Identification of insulin species by high-performance liquid chromatography

Objective: To identify the circulating species of insulin after separation by high-performance liquid chromatography (HPLC) in patients with factitious hypoglycemia. Research Design and Methods: In three of four patients presented, the diagnosis of surreptitious insulin injection was made by documenting the presence of animal insulin in the circulation after separation of the circulating insulin forms by HPLC. Results: Animal insulin was identified. Conclusions: Thus, the identification of the circulating form of insulin in the circulation by HPLC may be a useful adjunct in the diagnosis of factitious hypoglycemia if animal insulin has been injected and if the simultaneously measured concentrations of insulin and C-peptide are inconclusive.