Adult hypoglycaemia; a narrative review on forensic aspects

Forensic hypoglycaemia describes interactions between hypoglycaemia and the law. Hypoglycaemia, or more correctly the neuroglycopenia and associated temporary brain malfunction, may result in a state of automatism during which sufferers are absolved, in law, from responsibility for what would otherwise be a criminal offence. Courts consider hypoglycaemia beyond the experience of the layman and consequently require an expert to explain what it is and how it affects behaviour. Experts on hypoglycaemia are few reflecting the rarity with which hypoglycaemia occurs in all except patients with diabetes treated with hypoglycaemic agents. Experts on hypoglycaemia are drawn from a number of disciplines, toxicology, pharmacology, internal medicine, forensic pathology, endocrinology and clinical biochemistry of which the last three are the most important in the forensic context. Death from hypoglycaemia may be due either to natural underlying causes or from the hypoglycaemia. Hypoglycaemia is produced by accidental or malicious administration of hypoglycaemic agents of which insulin is the commonest. The purported victim may be alive or dead when first brought to medical attention. In the former, investigation is essentially the same as for any case of spontaneous hypoglycaemia. Investigation of suspected death from hypoglycaemia requires collaboration between a forensic pathologist and either a toxicologist or clinical biochemist. The post mortem measurement of blood glucose is of little or no value in the investigation of hypoglycaemia whereas detection and quantification of the pancreatic hormones insulin, C-peptide and proinsulin, preferably by liquid chromatography/mass-spectrometry (LC-MS), is essential. Vitreous humour is most useful fluid for analysis as all three hormones remain measurable for several days after death from insulin poisoning unlike in serum from peripheral blood. Biochemical and immunohistological analysis of tissue surrounding a suspected injection site, if identified, is also valuable.