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.

Post‐mortem determination of insulin using chemiluminescence enzyme immunoassay: preliminary results

“…Vitreous insulin levels determined by LC‐MS/MS in a population including 10 insulin‐dependent diabetic and non‐diabetic humans were found to be lower than the estimated limit of detection (0.1–0.2 ng/mL, corresponding to 2.4–4.8 μIU/mL) of the method by Thevis et al . Analogously, Hess et al . did not detect human insulin in vitreous humour in a series of 46 control cases.…”

“…Fatalities following insulin overdose in both diabetic and non‐diabetic individuals have been reported on occasion in clinical and forensic literature (Table ). In these cases, post‐mortem serum from femoral and cardiac blood as well as bile, vitreous humour, cerebrospinal fluid, and tissue samples have been analyzed for insulin and occasionally C‐peptide detection . Bile as a specimen was used in a unique case of a patient who had been admitted to hospital for 9 days after insulin administration .…”

“…Bile as a specimen was used in a unique case of a patient who had been admitted to hospital for 9 days after insulin administration . Though Coe reported that insulin and C‐peptide minimally penetrate the blood‐vitreous barrier, vitreous humour for insulin and C‐peptide measurements has been analyzed by numerous research teams in the past (mainly using a radioimmunoassay method) and more recently (using LC‐MS/MS) . In one case of fatal insulin intoxication, Junge et al .…”

“…As shown in Table , in the case of insulin intoxication reported by Thevis et al ., the vitreous insulin value determined by LC‐MS/MS was 1.0 ng/mL (corresponding to 172 pmol/L or 24.8 μIU/mL). Hess et al . found a concentration of 103 μIU/mL (corresponding to 715.3 pmol/L) using LC‐MS/MS in a case of suicide by insulin self‐injection.…”

“…This combination has been indicated as a suitable biological sample and reliable analytical method to provide evidence supporting and corroborating increased insulin concentrations as cause of death. Despite these encouraging findings, numerous unanswered questions remain in the forensic field concerning the most suitable biological matrix/matrices to analyze in alternative to post‐mortem serum in cases of fatal insulin intoxication …”