On January 11, 1922, something remarkable happened inside Toronto General Hospital — an event that would forever reshape the landscape of modern medicine. Leonard Thompson, a 14-year-old boy suffering from severe diabetes, received an insulin injection, making him the first human being ever treated with the hormone. What had once been a fatal diagnosis suddenly held the promise of becoming a manageable condition, ultimately changing the lives of millions of people around the world.
In the era before insulin entered the picture, being diagnosed with diabetes — especially type 1 — amounted to a death sentence. The symptoms were devastating: extreme weight loss, unquenchable thirst, and constant urination. On top of that, patients endured crushing fatigue, blurred vision, and in the worst cases, coma followed by death. Doctors had little to offer beyond a brutal starvation diet that provided scant relief and could only extend a patient's life by a handful of months.
The early 20th century saw a growing urgency in the search for an effective diabetes treatment. That search bore fruit in 1921, when Frederick Banting, a Canadian surgeon, teamed up with medical student Charles Best at the University of Toronto. Working under the direction of Professor John Macleod, the pair managed to isolate insulin from the pancreas of dogs. Biochemist James Collip subsequently came aboard, lending his specialized knowledge to purify the extract and make it safe enough for human administration. It was a true meeting of brilliant minds, all united by a shared mission.
Leonard Thompson's Historical Treatment
By the time Leonard Thompson's father rushed him to Toronto General Hospital, the boy was in dire straits. At a mere 65 pounds and drifting in and out of a diabetic coma, death seemed imminent. The first insulin injection came on January 11, 1922 — but the initial results were disheartening. Impurities in the extract triggered an allergic reaction, and doctors had no choice but to stop the treatment.
Collip, however, refused to give up. He threw himself into the painstaking work of further purifying the insulin. Twelve days later, on January 23, Leonard was given a second injection. This time, everything changed. His blood sugar levels fell dramatically, and his condition improved remarkably — all without adverse side effects. It was a watershed moment: the first successful use of insulin in a human patient, ushering in an entirely new chapter in the fight against diabetes.
The ripple effects of Leonard Thompson's successful treatment were both swift and far-reaching. Researchers at the University of Toronto partnered with pharmaceutical companies to scale up insulin production. This meant honing the extraction methods, implementing rigorous quality control, and building out distribution networks to reach patients everywhere. By the close of 1923, insulin had become widely accessible, revolutionizing how diabetes was managed and rescuing innumerable lives in the process.
To this day, the discovery of insulin stands as one of the crowning medical achievements of the 20th century. Beyond offering a vital lifeline to people living with diabetes, it opened doors to broader breakthroughs in endocrinology and laid the groundwork for the development of other hormone-based therapies.