Determination of hypoglycaemia induced by insulin or its synthetic analogues post mortem

Abstract

The determination of human insulin or its synthetic analogues in post-mortem specimens represents a challenge for forensic toxicologists due to its proven instability in post-mortem blood. We present two cases of an insulin-induced hypoglycaemia. In the first case, ante-mortem material was available for the detection of an injection with human insulin. Human insulin was detected by immunopurification with magnetic beads and liquid chromatography-tandem mass spectrometry (LC-MS/MS) analyses at a concentration of 5180 μU/ml. The molar ratio human insulin:C-peptide was 111. The second case describes a suicide by self-injection of Insulin lispro and determination of the drug after pre-extraction with methanol and immunopurification by LC-MS/MS at the injection site, in vitreous humour and organs. Apart from the well-known matrices--femoral blood and urine--the specimen vitreous humour and the injection site promise the best possibilities for a proof of insulin at autopsy. In addition to insulin analyses, the parameters C-peptide, proinsulin, glucose, lactate, and sulfonylureas should be measured in case of suspected fatal hypoglycaemia.

Keywords: LC-MS; hypoglycaemia; insulin; post mortem.