This Day in History — Insulin Is Successfully Isolated

The Off-Key Bard looks not to the stars this time, but into a cramped, sweltering Toronto laboratory where persistence, curiosity, and compassion brought millions back from the brink…

"There are discoveries that expand our understanding of the cosmos. And there are discoveries that give ordinary people the simple, priceless chance to keep living in it."

On this day in 1921, a small research team in a borrowed laboratory at the University of Toronto successfully isolated insulin — the pancreatic hormone responsible for regulating blood sugar. In doing so, they turned one of medicine's most relentless killers into a manageable condition, and eventually saved hundreds of millions of lives.

Before this breakthrough, a diagnosis of Type 1 diabetes was effectively a death sentence. The only available treatment was a severe low-calorie starvation diet — not a cure, but a slow extension of life by months before patients wasted away entirely.

The team working that summer consisted of surgeon Frederick Banting, 22-year-old medical student Charles Best, biochemist James Collip, and their supervisor, physiologist John Macleod, who had provided the lab space and left for a summer holiday in Scotland while the experiments proceeded. On this day in 1921, Banting and Best injected a diabetic dog with their crude pancreatic extract — which colleagues who saw it described as resembling "thick brown muck" — and watched its blood sugar levels drop to near-normal within hours.

What made Banting's approach work where others had failed was a single unconventional insight: he believed digestive enzymes in the pancreas were destroying the target hormone before it could be extracted. By first tying off the pancreatic ducts in the dogs, he allowed the enzyme-producing cells to degenerate while leaving the insulin-producing islet cells intact. It worked.

From a Dog's Recovery to a Dying Boy's

Collip spent weeks purifying the crude extract into something safe enough for human use. On January 11, 1922, 14-year-old Leonard Thompson — weighing just 65 pounds after years on the starvation diet, barely conscious — received the first human insulin injection at Toronto General Hospital. The first attempt caused a severe allergic reaction and had to be stopped. Collip refined the extract further over the following twelve days, and on January 23, Thompson received a second injection. His blood sugar stabilized. Within weeks he was visibly recovering, and he lived for another thirteen years.

By the end of 1922, fifty patients at Toronto General had been treated with insulin, ten of them revived from diabetic comas.

When it came time to patent the purification process, Banting, Best, and Collip signed the rights over to the University of Toronto for $1 each. The University immediately gave pharmaceutical companies royalty-free licenses to produce insulin. By 1923, it was in widespread commercial production.

That same year, the Nobel Prize in Physiology or Medicine was awarded to Banting and Macleod — a decision that provoked immediate controversy, since Best had done the original laboratory work alongside Banting from the start, and Collip's purification had made human treatment possible. Best was excluded because he had been a graduate student at the time of the experiments. Banting, furious at the slight, immediately announced he would split his prize money with Best. Macleod split his with Collip. The four men shared the money, if not the medal.

"No distant star, no mighty flame,
Yet countless lives would change the same…
For hope can come in drops so small,
And still become the greatest gift of all."

History reminds us: the true measure of a scientific breakthrough isn't always found in how far into the void it propels us — it's found in how many lives it wraps in hope and restores to health right here at home. And sometimes, the most important thing a discoverer can do after making history is sign the patent for a dollar and walk away.