Factitious hypoglycemia : "a never-ending story"?

Our team of diabetologist is challenged by the case of a 41 year-old woman with recurrent hypoglycaemic episodes. Her clinical background was complex with, among others, a neuroendocrine tumor, a nonalcoholic steatohepatitis and an adrenal insufficiency; these conditions require the exploration of several potential causes. After excluding an endogenous etiology, a factitious hypoglycemia was quicky suspected by clinicians. However, several venous samples showed normal insulinemia and a moderately decreased C-peptide. After multidisciplinary team discussion and facing a strong clinical suspicion, samples were sent to another laboratory to confirm the insulin results. Substantially supratherapeutics insulin concentrations were highlighted. This confirms the previous suspicion of surreptitious insulin administration with a recombinant form unrecognized by our routinely used analyzer. This observation leads us to briefly discuss the lack of cross-reactivities observed with many different insulin assays.