Drunkenness and/or hypoglycaemia are possible causes of unusual behavior in a person with diabetes. The aim of this study was to demonstrate different methods which were used in two contradictory reviews of experts for retrospective assessment of a patient's condition in the course of a car crash: An insulin-treated driver caused a car accident resulting in injuries to two men. He was accused of the crime of damage to health as well as of driving under the influence of an addictive drug. One expert, having seen the police and medical reports, concluded the driver was influenced by alcohol at the time of the accident. The contradictory argument of another expert, based on his own thorough investigation including self monitoring and completed by a model experiment, resulted in the conclusion that the driver was probably influenced by hypoglycaemia. Thus, the methods of the second expert seem to be useful reasonable tools to assess the unusual behavior of a person with diabetes.