Insulin and Oral Hypoglycemic Drug Overdose in Post-Mortem Investigations: A Literature Review

Two cases of fatal insulin homicide resolved using combined immunohistochemistry and immunofluorescence techniques

Diabetes is a prevalent disease in modern society. Since the development and widespread use of synthetic insulin, its therapeutic application has become globally recognized for managing diabetes. However, excessive administration of insulin may lead to fatal outcomes. The rapid pharmacokinetics of insulin in the human body, combined with the lack of distinct pathological changes, makes the forensic identification of fatal insulin overdose challenging. In this study, we present two cases of fatal insulin overdose, one with a postmortem interval of up to 28 days. Postmortem specimens were collected and analyzed. Immunohistochemical and immunofluorescence assays revealed the consistent distribution of insulin and protamine at the injection sites in both cases. Insulin and protamine particles were observed in the epidermis, epidermal cells, adipocyte membranes, inter-adipocyte spaces, inflammatory cells, and glandular structures. Toxicological analyses confirmed the presence of insulin in the injected skin, subcutaneous fat, blood, urine, vitreous humor, and bile. This study provides valuable insights and guidelines for the forensic identification of insulin overdose cases.

Intentional Insulin Overdose and Depression in Subjects with and Without Diabetes Mellitus: A Commentary

Insulin is an essential medication for people with type 1 diabetes mellitus and for some people with type 2 diabetes. Interestingly, insulin abuse has been reported as a mode of suicide, not only among people with diabetes, but also among their relatives, and among medical and paramedical personnel who have access to insulin. The aim of the present commentary was to raise awareness of potential depression-related intentional insulin overdose and its complications, as well as of the diagnosis and treatment of this entity. Insulin overdose may lead to severe and prolonged hypoglycemia, hypoglycemic coma, and death. Moreover, hypokalemia, hypomagnesemia, hypophosphatemia, and elevated liver enzymes are common. Insulin overdose should be suspected among people with diabetes in case of unexplained prolonged hypoglycemia and among people without diabetes who exhibit hypoglycemia and may have access to diabetic medications. The ratio of insulin to C-peptide helps distinguish exogenous insulin administration from endogenous secretion. The cornerstone of therapy is prompt administration of concentrated glucose infusions for days with simultaneous oral intake, when possible, and intense glucose monitoring to prevent hypoglycemia. Moreover, monitoring of serum electrolyte levels is recommended. Finally, psychiatric evaluation aiming at early identification of depression and suicidality is of paramount importance.

A retrospective study of 29 fatal cases of insulin overdose

PURPOSE

To summarize recent cases of fatal insulin poisoning both domestically and internationally, thereby offering valuable insights for the forensic identification of insulin overdose cases.

METHODS

Literature published since 2000 on fatal insulin overdose were systematically searched and screened. Data encompassing variables such as year, age, sex, cause of death, scene conditions, occupations, medical histories of victims and perpetrators, autopsy timing, dosage and administration methods, forensic pathology, and toxicological analysis, were compiled for rigorous statistical analysis.

RESULTS

Among the 29 fatal cases of insulin poisoning, suicides and homicides accounted for 55.2 % and 41.4 %, respectively. Precisely 34.5 % of victims or perpetrators were associated with the medical industry, 27.6 % had diabetes, and 24.1 % had mental illnesses such as depression. Intravenous injection resulted in quicker death than did subcutaneous injection. In some cases, immunohistochemical staining of insulin and protamine at injection sites yielded positive results. The average molar ratio of insulin to C-peptide in post-mortem blood was 13.76 ± 5.167, indicating a significant diagnostic value for insulin poisoning.

CONCLUSION

Assessment of cases of fatal insulin overdose should be thorough, incorporating case investigation, scene examination, medical records review, autopsy findings, pathological examinations, and laboratory tests, alongside considering the condition of the body and timing of death autopsy. Using mass spectrometry to detect insulin proves valuable, particularly in cases of poor body preservation.

Biochemical Toxicological Study of Insulin Overdose in Rats: A Forensic Perspective

Due to nonspecific pathological changes and the rapid degradation of insulin in postmortem blood samples, the identification of the cause of death during insulin overdose has always been a difficulty in forensic medicine. At present, there is a lack of studies on the toxicological changes and related mechanisms of an insulin overdose, and the specific molecular markers of insulin overdose are still unclear. In this study, an animal model of insulin overdose was established, and 24 SD rats were randomly divided into a control group, insulin overdose group, and a recovery group (n = 8). We detected the biochemical changes and analyzed the toxicological mechanism of an insulin overdose. The results showed that after insulin overdose, the rats developed irregular convulsions, Eclampsia, Opisthotonos, and other symptoms. The levels of glucose, glycogen, and C-peptide in the body decreased significantly, while the levels of lactate, insulin, and glucagon increased significantly. The decrease in plasma K+ was accompanied by the increase in skeletal muscle K+. The PI3K-AKT signaling pathway was significantly activated in skeletal muscle, and the translocation of GLUT4/Na+-K+-ATPase to sarcolemma was significantly increased. Rare glycogenic hepatopathy occurred in the recovery group after insulin overdose. Our study showed that insulin overdose also plays a role in skeletal muscle cells, mainly through the PI3K-Akt signaling pathway. Therefore, the detection of signaling pathway proteins of the skeletal muscle cell membrane GLUT4 and Na+-K+-ATPase has a certain auxiliary diagnostic value for forensic insulin overdose identification. Glycogen detection in the liver and skeletal muscle is important for the diagnosis of insulin overdose, but it still needs to be differentiated from other causes of death. Skeletal muscle has great potential for insulin detection, and the ratio of insulin to the C-peptide (I:C) can determine whether an exogenous insulin overdose is present.

Fourteen Deaths from Suspected Heparin Overdose in an Italian Primary-Level Hospital

Healthcare-related homicidal cases are not novel within the medical-legal landscape, but investigations are often made difficult with the scarcity of material evidence related to the crime. For this reason, it is necessary to carefully analyze the clinical documentation and employ ancillary forensic resources such as radiology, histopathology, and toxicology. In the presented scenario, the observation of 14 deaths from abnormal bleeding in a First-Level Italian Hospital revealed the administration of massive doses of heparin by a nurse. On behalf of the Judicial Authority, a multidisciplinary medical team investigated the case through the following steps: a thorough review of the clinical documentation, exhumation of the bodies belonging to the deceased patients, performing PMCT and autopsy, and collecting tissue samples for histopathological, immunohistochemical, and toxicological investigations. All the analyzed cases have been characterized by the observation of fatal hemorrhagic episodes not explained with the clinical conditions of the patients, confirmed using autopsy observations and the histological demonstration of the vitality of the lesions. However, due to the limited availability of biological material for the toxicological analysis, the indirect evidence from hematological analyses in hospitalized patients was crucial in demonstrating heparin overdose and its link to the recorded deaths. The present scenario demonstrates the fundamental importance of a multidisciplinary approach to cases of judicial interest related to the healthcare context. Therefore, the illustrated methodologies can be interpreted as an operational framework for similar future cases.

Insulin murder and the case of Colin Norris

Although insulin is an essential medicine and a life-saving drug, it has also been incriminated in many poisoning deaths; accidental, suicidal and some with malicious intent. Overdosing with insulin precipitates a life-threatening state of hypoglycemia and if untreated leads to coma, irreversible brain damage and death. Normally, the pancreatic β-cells secrete equimolar amounts of insulin and C-peptide into the portal venous blood, although under physiological conditions the plasma concentration ratio (insulin/C-peptide) is less than unity, because insulin is more susceptible to hepatic first-pass metabolism. A high ratio of insulin/C-peptide in plasma from a poisoned patient is compelling evidence that pharmaceutical insulin was administered, which does not contain C-peptide. The analysis of insulin and C-peptide was traditionally done by immunoassay methods (RIA and/or ELISA), although high resolution LC-MS/MS is more suitable for forensic purposes and permits the identification of insulin analogues. Use of insulin as a murder weapon is exemplified by the case of Colin Norris, a male nurse found guilty of murdering four elderly patients and the attempted murder of a fifth by injecting them with insulin. However, the prosecution evidence against Norris was mainly circumstantial and hearsay. Toxicological evidence against Norris consisted of a high insulin/C-peptide concentration ratio in plasma from one of the victims. This analysis was done by an immunoassay method at a clinical laboratory and not a forensic laboratory. Analytical procedures, including chain-of-custody routines, are more stringent at forensic laboratories. Since his conviction, some of the medical evidence against Norris has been called into question, especially the prevalence of spontaneous attacks of hypoglycemia in elderly and frail patients with co-morbidities.