Is it really possible to kill with insulin without leaving traces? From lifesaver to killer, the issues surrounding the analytical characterization of postmortem insulin illustrated by an exemplary case.

Evidence of an insulin overdose is very complicated in the medico-legal field. The analysis and subsequent interpretation of results is complex, especially when treating postmortem blood samples. The instability of insulin, the special pre-analytical conditions and the absence of specific analytical methods has led most laboratories not to analyze insulin in their routine with a consequent underestimation of cases. This paper aims to assess the difficulties associated with the analytical characterization of insulin by describing a case that typically represents most of the inconveniences encountered following a suspected insulin overdose. The case concerns a man found dead at home by his brother. After an external examination, which did not reveal a specific cause of death, toxicological analysis was requested which did not reveal any substance of toxicological interest. Only 9 months later, it was reported to the toxicologist that the subject was diabetic, on insulin lispro treatment and that three empty syringes were found next to his body. Following analysis by LC-high-resolution mass spectrometry, the presence of insulin lispro at a concentration of 1.1 ng/mL, a therapeutic concentration, was evidenced. Despite the low concentration found, overdose cannot be excluded and this paper will describe the criteria evaluated to reach this conclusion. This case highlights that the interpretation of a postmortem insulin concentration is very complex and requires the evaluation of various elements including the circumstances of death, the subject's medical history, the interval between death and sampling and the sample storage.

Suicide by injecting lispro insulin with an intravenous cannula.

Suicide by injecting insulin is not uncommon both in diabetic and non-diabetic people. The victim usually uses an insulin syringe or a traditional syringe attached to a needle for the injection of insulin, of either animal or synthetic origin. We report a case of suicide by a non-diabetic physician by injecting lispro insulin through an intravenous cannula. To the best of our knowledge, the use of an intravenous cannula for the injection of insulin for suicide is unusual and is rarely reported in the medico-legal literature.

Massive insulin overdose managed by monitoring daily insulin levels.

We present a case of a significant insulin overdose that was managed by monitoring daily plasma insulin levels. A 39-year-old male with poorly controlled diabetes mellitus presented to the Emergency Department via emergency medical services after an attempted suicide by insulin overdose. In the attempted suicide, he injected 800 U of insulin lispro and 3800 U of insulin glargine subcutaneously over several parts of his abdomen. The patient was conscious upon arrival to the emergency department. His vital parameters were within normal range. The abdominal examination, in particular, was nonfocal and showed no evidence of hematomas. He was awake, alert, conversant, tearful, and without any focal deficits. An infusion of 10% dextrose was begun at 100 mL/h with hourly blood glucose (BG) checks. The patient was transferred to the intensive care unit where his BG began to decrease and fluctuate between 50 and 80 mg/dL, and the rate of 10% dextrose was increased to 200 mL/h where it was maintained for the next 48 hours. The initial plasma insulin level was found to be 3712.6 uU/mL (reference range 2.6-31.1 uU/mL). At 10 hours, this had decreased to 1582.1 uU/ml. On five occasions, supplemental dextrose was needed when the BG was <70 mg/dL. Thirty-four hours after admission, the plasma insulin level was 724.8 uU/mL. Fifty-eight hours after admission, the plasma insulin level was 321.2 uU/mL, and the 10% dextrose infusion was changed to 5% dextrose solution at 200 mL/h. The plasma insulin levels continued to fall daily to 112.7 uU/mL at 80 hours and to 30.4 uU/mL at 108 hours. He was transferred to an inpatient psychiatric facility 109 hours after initial presentation. Monitoring daily plasma insulin levels and adjusting treatment on a day-to-day basis in terms of basal glucose infusions provides fewer opportunities for episodic hypoglycemia. Furthermore, it was easier to predict daily glucose requirements and eventual medical clearance based on the plasma levels.