As Philippus Aureolus Theophrastus Bombastus von Hohenheim, a famed sixteenth-century alchemist and physician, explained, “It is the dose that makes the poison.” Taken from a section in Neil Bradbury’s book A Taste for Poison, this statement could not be more true in his telling of the fine line between insulin as a lifesaving drug and a deadly toxin.
A group of Canadian researchers discovered insulin in 1921 upon discovering they were able to create a diabetes disease state in dogs upon the removal of the pancreas. The revolutionary identification of this vital compound marked a turning point in the treatment of diabetes which, up until that point, was a fatal diagnosis.
Insulin itself is a hormone produced by the pancreas and is responsible for the regulation of glucose metabolism. It manages this task by promoting glucose uptake from the bloodstream and into the cells where it can be converted into glycogen and stored in places such as the liver and muscles. When consuming a meal high in sugars or carbs, blood glucose levels rise and cause the pancreas to secrete insulin.
To understand the effects insulin has on the body when in excess or limited, Bradbury opens with a story about the murder of a woman named Elizabeth Barlow. Elizabeth, often called Betty, was a young woman from Yorkshire who lived with her husband Kenneth Barlow. The pair both spent time working as nurses, which becomes important later in the story.
When Elizabeth was found dead on a Saturday morning in 1957, the initial conclusion of the investigation was that her death had been a tragic accident. One critical detail about her presentation, however, proved essential in the determination of the true nature of the event.
The story began when Elizabeth returned home early from work one day cheerful as ever (and with fish and chips for dinner nonetheless!) After sitting down to watch the ‘telly’ with her husband, Elizabeth began to feel tired and delirious. At around 6:30 p.m. she retired to bed, complaining that she was “too comfortable to move.” By this time the effects of the poisoning were already evident.
As the night dragged on, Elizabeth experienced nausea, vomiting, and intense overheating. By 11:20 p.m., she started a cold bath in an effort to cool off. As Kenneth later testified, he found her dead in the bathtub after working tirelessly to save her, but he was unsuccessful.
Investigations later revealed several clues that ruled out the possibility of her death being due to natural causes. Chief among these reasons were remarkably dilated pupils and her body’s inability to regulate her temperature. All this can be explained when we consider that glucose levels in the body are typically kept within narrow limits and that dipping below these constraints (hypoglycemia) means that there is not enough energy for the body to perform its necessary functions. In a pinch, the brain is the first to suffer from a glucose shortage given the organ’s inability to store glucose. As noted by her state of delirium and exhaustion, Elizabeth was experiencing the symptoms of a brain deficient in energy.
It was later found that her husband had poisoned her with an excess of insulin which, having the ability to prevent the cellular uptake of glucose, resulted in a full-body depletion and her unfortunate demise.
Ultimately Kenneth was found guilty of Elizabeth’s murder, but this story serves as a reminder that while insulin is a lifesaving drug for millions of people with diabetes, it can also be a deadly toxin when the dosage is altered.
~ Victoria Melehov `26