Determining the cause of death in diabetics is often challenging, especially due to the need to perform an autopsy within a short time after death due to the rapid degradation of relevant biological markers (insulin, glucose, C-peptide, etc.) [3, 4].

Diabetic patients may be at imminent risk of death if acute complications of diabetes (hypoglycemia or hyperglycemia) occur [5, 6]. Hyperglycemia is characterized by glycosuria, osmotic diuresis, and severe dehydration of the body, all of which can eventually lead to the disruption of the internal environment and to impaired consciousness [7]. Type I diabetics are also at risk of the accumulation of ketones formed in the liver, which can lead to ketoacidotic coma [8, 9].

In clinical practice, hypoglycemia (blood glucose falling below 3.9 mmol/L) is a frequently encountered complication in Type I diabetics on insulin therapy. It is usually caused by an inadequate insulin dose, excessive physical activity, or reduced food intake [10, 11].

In the presented case, a woman with Type I diabetes used methamphetamine as documented by both the witness testimonies and the results of the toxicological analysis. Methamphetamine is known for its stimulant effects, manifested by a feeling of a significant increase in energy, relaxation, and euphoria, which are accompanied by increased glucose consumption. In addition, methamphetamine is known to suppress appetite, which can also lead to the development of hypoglycemia in patients with Type I diabetes [12]. It has to be noted that in individuals with no pre-existing medical condition (such as Type I diabetes), the concentration of methamphetamine detected in the blood of the deceased woman is not usually life-threatening [13]. Furthermore, the autopsy and subsequent histological examination did not reveal any signs of known serious acute complications associated with methamphetamine and amphetamine use (myocardial infarction, cerebral hemorrhage) [14]. On the other hand, long-term users may develop homeostasis disruption that can potentially lead to death [15].

In addition to general congestion of the organism, lung and brain edemas were found during the autopsy. These signs may have developed as a result of the detected hypoglycemia, but they might have also resulted from the resuscitation. The same is to be said for the frothy, bloody content of the airways and the congestion of the lungs. These findings are common after unsuccessful resuscitation.

In the presented case, the development of convulsions and collapse could have been provoked by hypoglycemia as a result of Type I diabetes, hypoglycemia due to methamphetamine abuse, but also due to a combination of both these factors [10, 16]. After the development of convulsions, the woman was given insulin which was not indicated as evidenced by the results of the biochemical analysis. In this case, it is reasonable to assume that the fatal homeostasis disruption was caused by hypoglycemia induced by a combination of all these factors. Unfortunately, forensic practice cannot provide a definitive answer to the question of whether any of these factors alone would be capable of causing death in this case, nor can it quantify the contribution of each to the fatal outcome.

The court and the prosecution were then faced with the difficult task of determining the role of the two men in the death of the young woman and their guilt. In the Czech Republic, crimes of negligence are tried in district courts, while criminal acts involving death due to the influence of drugs are tried in regional (higher degree) courts. In effect, each of the defendants was tried in a different court with a different panel of judges. The man who provided the woman with methamphetamine was charged by the prosecutor with the offense of illicit production and dealing with narcotic drugs, psychotropic substances, and poisons, which is punishable by 10–18 years of imprisonment [1]. The first instance court ruled that the direct causal link between the administration of methamphetamine and death could not be proved beyond a reasonable doubt and sentenced the defendant to 5 years in a maximum-security prison for the distribution of an addictive substance. The appellate court, however, ruled that the causal link existed, even though it could not have been quantified, and convicted the defendant of causing death by providing an illicit narcotic substance, sentencing him to 11 years in a maximum-security prison.

The partner of the deceased woman who administered insulin was charged with manslaughter by negligence, with a penalty of up to three years. In his case, the court requested an additional expert opinion from the field of internal medicine for a specific statement on the possible role of insulin in the case. The expert’s report concluded that the amount of insulin mentioned in the witness statement would not endanger the life of a well-treated diabetic. The amount of the actually administered insulin could, however, not have been verified. The expert was unable to comment with certainty on whether the woman’s life could have been saved at the time when her convulsions started if she had received no insulin. Although it is clear that the administration of insulin to hypoglycemic patients aggravates hypoglycemia, thereby reducing the possible chances of rescue, the court had to take into account the fact that neither the post-mortem laboratory examination nor any other expert examination could prove beyond reasonable doubt that the woman died as a result of hypoglycemia aggravated by the administration of insulin and, therefore, the court relied on the principle of in dubio pro reo. For these reasons, the defendant was eventually acquitted of all charges, even though he had no expertise or training to handle and administer drugs to another person.

In conclusion, we presented a case of a young female diabetic patient on insulin therapy whose death resulted from a combination of her illness, the use of methamphetamine, and insulin. In forensic practice, it is very difficult (sometimes even impossible) to quantify the contribution of individual factors to death in similar cases. Such equivocal conclusions, when a direct link between the administration of a foreign substance and the death cannot be proven, put the law enforcement authorities in a difficult position.