Fatal suicides by insulin injection: a retrospective medico-legal case series from Türkiye

Fatal insulin overdose remains a persistent diagnostic challenge in forensic practice, particularly when postmortem biochemical confirmation is limited or unavailable. This study retrospectively examined seven suicide deaths involving insulin-induced hypoglycemia adjudicated by the First Specialization Board of the Council of Forensic Medicine in Türkiye between 2011 and 2024. Case files, scene findings, psychiatric histories, insulin accessibility, toxicology data, and autopsy and histopathology reports were systematically reviewed. The decedents ranged from 30 to 81 years of age; four had diabetes mellitus requiring insulin therapy, while three had no therapeutic indication for insulin and obtained it through non-medical means. Most had documented suicidal behavior, and two had previously attempted self-harm specifically with insulin. Scene investigations frequently revealed insulin delivery devices, and vitreous glucose levels—when available—were low. Autopsy examinations demonstrated non-specific hypoxic-ischemic changes without pathognomonic indicators of insulin toxicity. Because postmortem biochemical instability and limited analytical capacity constrained insulin or analogue quantification, final determinations relied on a convergent evaluation integrating behavioral intent, access pathways, scene reconstruction, and exclusion of alternative causes. These findings underscore the importance of contextual medico-legal reasoning in classifying insulin-related deaths and provide a practical interpretive framework for situations in which toxicological confirmation is technically restricted.