The discovery of insulin in 1921 by Sir Frederick G. Banting, Charles H. Best, and J.J.R. Macleod at the University of Toronto stands as one of the most significant medical breakthroughs in history.
Later refined by James B. Collip, this life-saving hormone has since saved millions of lives and paved the way for a century of advancements in diabetes care. Here’s a look at the remarkable journey that brought insulin to the world.
7 November 1920 – A Spark of Inspiration
By 1920, scientists had identified clusters of cells in the pancreas, known as islets, responsible for producing insulin. They also discovered that these cells are destroyed in type 1 diabetes, leading to the condition.
While earlier attempts to extract insulin from ground-up pancreas cells had failed, the challenge remained: how to isolate insulin without destroying it in the process.
That October, Frederick Banting, a Canadian surgeon, read an article suggesting that insulin-producing cells deteriorate more slowly than other pancreatic tissue. This sparked an idea: perhaps insulin could be extracted by breaking down the pancreas in a way that preserved these vital cells.
However, Banting lacked the scientific expertise to test his theory alone. On 7 November 1920, he approached John Macleod, a prominent professor at the University of Toronto. Together, they devised a plan to explore this groundbreaking possibility.
17 May 1921 – The Experiments Begin
Macleod provided Banting with laboratory space and enlisted Charles Best, a research student skilled in measuring blood glucose levels, to assist. Their experiments began on 17 May 1921, focusing on extracting insulin from a dog’s pancreas.
Their method involved tying off the pancreatic duct to destroy other substances in the pancreas that could break down insulin, leaving the islets intact. The resulting extract was then administered to dogs whose pancreases had been removed, allowing the team to observe its effects on blood sugar levels.
12 December 1921 – A Breakthrough in Purity
James Collip, a biochemist, joined the team in December 1921 to refine the insulin extract, making it safe for human use. Using cattle pancreases, Collip developed a purer and more concentrated form of insulin, marking a critical step toward clinical application.
11 January 1922 – Insulin’s First Human Trial
In January 1922, Leonard Thompson, a 14-year-old boy on the brink of death from type 1 diabetes, became the first person to receive an insulin injection. While his dangerously high blood sugar levels dropped within 24 hours, an abscess formed at the injection site, and his ketone levels remained elevated.
Collip worked tirelessly to further purify the extract. On 23 January 1922, Leonard received a second injection. This time, the results were extraordinary: his blood sugar levels normalized, and he experienced no significant side effects. For the first time in history, type 1 diabetes was no longer a death sentence.
3 May 1922 – Insulin Takes the Stage
On 3 May 1922, Macleod presented the team’s findings to the international medical community at a meeting of the Association of American Physicians in Washington. Titled The Effects Produced on Diabetes by Extracts of Pancreas, the paper introduced the term “insulin” for the first time. The audience responded with a standing ovation, recognizing the monumental impact of this discovery.
23 January 1923 – Insulin for the World
Banting, Collip, and Best were awarded U.S. patents for insulin and its production method on 23 January 1923. In a gesture of extraordinary generosity, they sold the patents to the University of Toronto for just $1 each. Banting famously declared, “Insulin does not belong to me, it belongs to the world,” ensuring that the treatment would be accessible to all who needed it.
15 October 1923 – Mass Production Begins
As demand for insulin soared, the team refined their production techniques to meet global needs. In October 1923, Eli Lilly became the first company to mass-produce insulin, shipping the first commercial supply and making the treatment widely available.
25 October 1923 – A Nobel Prize for Life-Saving Work
In recognition of their groundbreaking achievement, Banting and Macleod were jointly awarded the 1923 Nobel Prize in Physiology or Medicine. Banting shared his prize money with Best, while Macleod shared his with Collip, acknowledging the collaborative effort behind the discovery.
1934 – Diabetes UK is Founded
In 1934, novelist H.G. Wells and Dr. R.D. Lawrence, both living with type 1 diabetes, established the Diabetic Association (now Diabetes UK). Their mission was to ensure that everyone in the UK, regardless of financial circumstances, had access to insulin.
Over the decades, Diabetes UK has funded groundbreaking research, including the development of the first insulin pen and pump, national eye screening programs to prevent sight loss, and the establishment of the UK’s first diabetes foot clinic to reduce amputations. Their DiRECT trial has also shown promising results in putting type 2 diabetes into remission.
A Legacy of Hope
The discovery of insulin not only transformed diabetes care but also ignited a century of innovation. Today, thanks to the dedication of researchers, healthcare professionals, and organizations like Diabetes UK, millions of people worldwide live healthier, fuller lives. Yet, the work is far from over. With more lives to change and more breakthroughs to achieve, the journey that began in 1921 continues to inspire hope and progress.
Source: Diabetes org
