The Boy Who Changed Medicine Forever
In early January 1922, a fourteen-year-old boy lay dying in a hospital bed in Toronto.
Leonard Thompson weighed just 65 pounds. His limbs were thin and fragile. His cheeks were hollow. His hair had begun to fall out. When he breathed, doctors smelled acetone on his breath—a sign that his body was slowly poisoning itself. He drifted in and out of consciousness, slipping toward a diabetic coma.
Three years earlier, Leonard had been diagnosed with Type 1 diabetes. In 1919, that diagnosis was a death sentence.
There was no insulin. No treatment. No cure.
Doctors could only delay the inevitable.
Their only tool was starvation.
They called it “careful dietary regulation.” Leonard was allowed no more than 450 calories a day. Sometimes less. The reasoning was cruel but simple: if sugar was killing him, then he must eat almost nothing that could turn into sugar.
The diet slowed his decline—but it also destroyed him.
Children with diabetes wasted away on these starvation diets. Some survived a year. Many didn’t. They died from malnutrition if the disease didn’t claim them first. Parents watched helplessly as their children faded, day by day.
By December 1921, Leonard Thompson was out of time.
His parents, Harry and Florence Thompson, brought him to Toronto General Hospital as a last hope. Leonard was skeletal. Weak. Barely conscious.
Doctors were honest with Harry Thompson.
Your son is dying.
Conventional medicine has nothing left to offer.
But there was one other option.
Experimental. Untested. Never before used in a human being.
Harry Thompson faced an impossible choice.
At the same time, just a few miles away, a young surgeon named Frederick Banting was pursuing a radical idea in a crude laboratory at the University of Toronto.
Banting believed the pancreas produced an internal substance that controlled blood sugar. If that substance could be isolated and injected, perhaps diabetes could be treated.
The idea was not entirely new—but no one had made it work.
When Banting presented his theory to Professor John Macleod, a leading diabetes expert, he was met with skepticism. Still, Macleod agreed to give him minimal support: a small laboratory, a few dogs, and a medical student named Charles Best.
Throughout the summer of 1921, Banting and Best worked relentlessly. They removed pancreases from dogs, induced diabetes, and injected them with pancreatic extracts.
The results were undeniable.
Blood sugar levels dropped. Symptoms improved. Dogs near death recovered.
Yet other scientists dismissed their work. The extract was crude. Impure. One researcher sneered that it looked like “thick brown muck.”
By November 1921, Banting and Best presented their findings. With biochemist James Collip now helping refine the extract—and Macleod overseeing the work—they believed they might finally be ready to try it in a human.
They needed someone desperate enough to take the risk.
Leonard Thompson was that patient.
On January 11, 1922, Leonard received the first injection of pancreatic extract ever given to a human.
His father stood nearby, watching, hoping for a miracle.
It didn’t come.
The extract was too impure. Leonard developed hives and a mild allergic reaction. His blood sugar barely changed.
The first human trial had failed.
They could have stopped there.
They didn’t.
James Collip returned to the lab and worked day and night to purify the extract—refining the alcohol process, removing contaminants, concentrating the active compound.
Twelve days passed.
Twelve days of Leonard growing weaker.
Twelve days of waiting.
On January 23, 1922, Leonard received a second injection.
This time, everything changed.
Within hours, his blood sugar dropped to near-normal levels. The acetone smell vanished. His breathing steadied. His mind cleared.
Doctors recorded the moment simply:
“The boy became brighter, more active, looked better and said he felt stronger.”
Leonard Thompson began to recover.
He received daily injections. He gained weight. Color returned to his face. Strength returned to his body.
In May 1922, Leonard went home.
The news spread rapidly around the world.
A dying child had lived.
A disease that had been fatal for thousands of years now had a treatment.
But success brought a new crisis: demand.
Parents flooded the University of Toronto with letters—begging, pleading, praying for insulin. The team struggled to produce enough. Some batches failed. Supplies ran short. Leonard himself survived on inconsistent injections for months.
In mid-1922, pharmaceutical company Eli Lilly partnered with the university. By 1923, insulin was being produced on a large scale and distributed worldwide.
Children lived.
Parents planned futures instead of funerals.
In October 1923—just twenty-one months after Leonard’s recovery—the Nobel Prize in Medicine was awarded to Frederick Banting and John Macleod.
Banting immediately shared his prize money with Charles Best. Macleod shared his with James Collip.
All four knew the truth.
This was a collective achievement.
And it began with one father’s courage.
Leonard Thompson lived thirteen more years.
He grew up. He lived.
On April 20, 1935, he died of pneumonia at age 27—not from diabetes.
Without insulin, he would have died at fourteen.
Today, millions of people live because he was first.
Leonard Thompson was the bridge between certain death and manageable life.
One boy.
One injection.
One impossible choice.
That wasn’t just medicine advancing.
That was a revolution.
