The story of insulin – Part 1: Saving a boy’s life.

The discovery of insulin treatment 100 years ago became a race against time to save a teenage boy’s life. Here’s that story.

Leonard Thompson, the first person treated with insulin.

Leonard Thompson was dying. It was January 1922 and the Canadian boy was just 14-years old.

Some three years earlier, Leonard had been diagnosed with type 1 diabetes. Insulin therapy had yet to be discovered, so he was put on the only known treatment at the time for sustained hyperglycemia: a starvation diet.

Leonard lived on grapefruit, small amounts of meat, and vegetables that had been boiled three times. He was also given whiskey on occasion to numb his constant hunger. A 14-year-old boy should consume between 2,000 and 3,000 calories per day. Leonard was surviving on fewer than 500.

The sparse diet was simply an attempt to prolong Leonard’s life by a few years. It would not save his body from the damage caused by sustained high blood glucose levels. On 2nd December 1921, Leonard was carried into Toronto General Hospital by his father Harold Thompson. The boy weighed less than 30 kilograms.

In the words of Stella Clutton, Secretary to the hospital’s Chief Physician, she had “never seen a living creature as thin as he was.” Leonard was deathly pale, his hair was falling out and his abdomen was bloated. The boy’s breath was heavy with the odor of acetone from ketoacidosis, the coma-inducing chemical process that poisons the body with ketones when blood glucose levels are too high for too long. Leonard’s death was seemingly imminent.

“They focused all their efforts on purifying insulin enough for its first clinical test on a human subject. That subject would be Leonard Thompson.”

Saved by science.

Fortune may not have favored Leonard in his early years, but that was about to change.

A few months earlier, in the spring of 1921, a Canadian scientist and physician named Frederick Banting had traveled to the University of Toronto to seek support for his theory on extracting insulin from animals.

Banting was soon partnered with undergraduate Charles Best, and on 30th July 1921 the pair successfully isolated an extract from the pancreas of a healthy dog and injected it into a dog with diabetes. Within an hour, the diabetic dog’s blood glucose had fallen by 40%. Banting and Best had discovered insulin treatment for diabetes.

They presented their results to the university’s Professor of Physiology, J.J.R. Macleod, and were given a better laboratory and more advanced equipment. It was then that Banting came upon the idea of extracting insulin from a cow pancreas, which the team was able to do by December 2021. After that they focused all their efforts on purifying insulin enough for its first clinical test on a human subject. That subject would be Leonard Thompson.

Frederick Banting and Charles Best at the University of Toronto.

Between life and death.

It’s hard to imagine the conversation that must have taken place between Leonard’s father and the hospital’s most senior doctors. But there was surely a point at which Harold Thompson made the difficult decision to allow the physicians to treat his son with the experimental insulin. On 11th January 1922, as he slipped into and out of a diabetic coma, Leonard Thompson became the first person to receive an injection of insulin.

The result was mixed.

The insulin did succeed in bringing Leonard’s blood glucose down, from 24.4 mmol/L to 18 mmol/L (fasting blood glucose for someone without diabetes is around 5 mmol/L). But Leonard’s ketones remained high.

The research team, now assisted by biochemist James Collip, determined that the insulin had not been pure enough. Records describe it as “a thick brown muck” that was so impure it caused Leonard a severe abscess on the injection site.

“Banting, Best and Collip went from bed to bed injecting each child with the newly-developed insulin. Before they had reached the last child, the first ones to receive the injection were waking up from their comas.”

For the next 12 days, Collip worked tirelessly to improve the quality of the insulin. On 23rd January 1922, it was again injected into Leonard. This time, the result would change diabetes treatment forever.

Leonard’s blood glucose fell from 28.8 mmol/L to 6.7 mmol/L, and his ketones were eliminated. Insulin had saved his life.

In those days, children with end-stage diabetic ketoacidosis were kept in wards. Many of the children would be comatose, with family members grieving at their bedsides. Banting, Best and Collip went from bed to bed injecting each child with the newly-developed insulin. Before they had reached the last child, the first ones to receive the injection were waking up from their comas.

Frederick Banting’s and Charles Best’s laboratory.

Leonard’s legacy lives on.

In May 1922, a much stronger Leonard Thompson was discharged from Toronto General Hospital. He would go on to become a clerk for a drug company and continued to inject insulin for the rest of his life. Leonard eventually succumbed to pneumonia in 1935 at the tender age of 27.

The discovery of insulin 100 years ago is a story of personal bravery, scientific persistence and the human capacity for care. Thanks to Leonard and the people who treated him, millions of people now use insulin every day to manage their diabetes. Times have changed and technology has advanced, but the experience of 14-year-old Leonard Thompson remains one of the most fundamental events in medical history.

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