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13:00in productionCh. 1 · An idea born from a lecture/ 13:00 · ceiling 15 min
Medicine

Insulin

In 1921 Frederick Banting, Charles Best, John Macleod and James Collip at the University of Toronto isolated and purified insulin from animal pancreases, turning a previously fatal diagnosis into a manageable condition within months.

Acting on an idea about protecting insulin-producing cells during extraction, Frederick Banting worked with Charles Best in John Macleod's laboratory at the University of Toronto through 1921 to isolate insulin from dog and, later, calf and adult pancreases. Biochemist James Collip then purified the extract well enough for human use, and on 11 January 1922 fourteen-year-old Leonard Thompson became the first patient treated with it at Toronto General Hospital. Banting and Macleod shared the 1923 Nobel Prize in Physiology or Medicine, a decision that left out Best and Collip and became a lasting point of controversy, though Banting and Macleod each split their prize money with their respective collaborators.

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Chapters & takeaways6
  1. 0:08
    An idea born from a lecture

    Preparing a lecture on the pancreas in November 1920, Banting hit on a way to isolate insulin without it being destroyed by digestive enzymes.

  2. 2:10
    From dog pancreases to calf fetuses

    Working with Charles Best through 1921, Banting extracted insulin first from dog pancreases and then found fetal calf pancreases worked just as well.

  3. 4:20
    Purifying the extract for people

    Biochemist James Collip joined the team to refine the extract into something safe and effective enough to give to a patient.

  4. 6:30
    The first injection, January 1922

    On 11 January 1922, fourteen-year-old Leonard Thompson became the first person treated with insulin at Toronto General Hospital.

  5. 8:40
    A Nobel Prize that left names out

    The 1923 Nobel Prize went only to Banting and Macleod, a decision both men addressed by sharing their prize money with Best and Collip.

  6. 10:50
    From a death sentence to a managed condition

    Worth an hour because within about a year, a diagnosis that had reliably meant death became one that could be treated indefinitely.

Worth your time?

Yes. Study the whole thing.

5/ 5
What works
  • the speed of it, an idea in November 1920 to a treated patient by January 1922
  • the practical problem-solving, switching to fetal calf pancreases when adult ones were harder to source
  • the candour about the Nobel Prize dispute rather than presenting a tidy four-person triumph
What does not
  • it does not fully resolve who deserves how much credit, only that Best and Collip were left off the official prize
  • it does not detail how insulin production was scaled up industrially beyond noting that it happened
Study it if
  • readers who want the concrete timeline behind a treatment used by millions daily
  • anyone interested in how scientific credit gets allocated, and disputed
  • students of twentieth-century medical history
Skip it if
  • readers wanting the biochemistry of how insulin regulates blood sugar
  • anyone after a dispute-free account of who deserves credit
The written brief3 min read

An idea born from a lecture

In November 1920, Frederick Banting, then a young surgeon, was preparing a lecture on the pancreas at the University of Western Ontario when he read that diabetes was thought to result from a missing hormone normally secreted by clusters of cells in the pancreas called the islets of Langerhans. The obstacle to isolating that hormone was that the pancreas also produces digestive enzymes, including trypsin, that break down proteins, destroying any hormone extracted alongside them before it could be used. Banting’s idea, drawn from a 1920 paper by Moses Barron describing what happens when a pancreatic duct is blocked, was that tying off the duct would destroy the enzyme-producing tissue while leaving the hormone-producing islets intact, making a usable extract possible.

From dog pancreases to calf fetuses

Banting brought the idea to John Macleod, a physiology professor at the University of Toronto, who provided laboratory space and assigned a student, Charles Best, to assist him. Through 1921 the two men worked with dog pancreases, tying off the ducts, waiting for the digestive tissue to degenerate, and then extracting the remaining material to test on diabetic dogs. In November 1921, needing a more practical source of tissue, Banting obtained pancreases from fetal calves at a slaughterhouse and found the extracts worked just as well as those from dogs; by December he had also succeeded in extracting the hormone from adult pancreases, expanding the available supply.

Purifying the extract for people

The extract that worked in dogs was still too impure and inconsistent for safe use in a person, and biochemist James Collip joined the team specifically to solve that problem, developing purification methods that removed enough of the contaminating material to make the hormone, by then called insulin, suitable for human injection. That purification step was not incidental; without it, the raw pancreatic extracts that had treated diabetic dogs were not reliable enough to give to a patient, and Collip’s contribution sat between the initial biological finding and its first clinical use.

The first injection, January 1922

On 11 January 1922, fourteen-year-old Leonard Thompson, a patient at Toronto General Hospital, became the first person treated with insulin, a moment that turned a laboratory finding into a medical treatment within roughly a year of Banting’s original idea. Diabetes at the time, particularly the form now known as type 1, was a condition that reliably killed patients, often within months of diagnosis, through starvation-based management that could delay but not prevent death. By the spring of 1922, Banting had opened a private practice specifically to treat diabetic patients with the new extract, and industrial-scale production followed soon after, extending the treatment well beyond the original Toronto laboratory.

A Nobel Prize that left names out

Recognition for the discovery proved contentious. The 1923 Nobel Prize in Physiology or Medicine went to Banting and Macleod alone, a decision that excluded Best, who had done much of the hands-on laboratory work alongside Banting, and Collip, whose purification method had made human treatment possible in the first place. Both prize recipients responded by splitting their winnings, Banting sharing his half with Best and Macleod sharing his with Collip, an informal correction to a formal recognition that many at the time and since have regarded as too narrow given how collaborative the underlying work had been.

From a death sentence to a managed condition

This is worth understanding because it compresses an entire arc, a specific biochemical problem, a plausible solution, animal testing, purification, and a first human patient, into about fourteen months, a pace that is unusual even by the standards of medical discovery. It is also a clear-eyed case study in how scientific credit does not always track scientific contribution, since the two collaborators without a Nobel medal, Best and Collip, did work that later biographers and historians generally regard as indispensable. An hour spent on the full sequence gives a fuller picture than the shorthand version, in which insulin’s discovery is often reduced to Banting’s name alone.

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