Insulin as a treatment for diabetes was discovered in 1921 by a team in Toronto: Sir Frederick Banting, Charles Best, John J.R. Macleod, and James Collip.

Quick Scoop: Who “invented” insulin?

If you’re asking “who invented insulin for diabetes,” you’re really asking who first discovered and purified the hormone so it could be used as a life‑saving drug.

  • The key figure most people name is Sir Frederick Banting , a Canadian surgeon who had the original experimental idea and drove the early work.
  • He worked with Charles Best , a young medical student who helped perform the dog experiments that first showed insulin could lower blood sugar.
  • Their work was supervised by John J.R. Macleod , a physiology professor at the University of Toronto who provided the lab, animals, and scientific guidance.
  • James Collip , a biochemist, then purified the pancreatic extract so it was safe and effective for human use, turning a lab discovery into a real medicine.

So, insulin was not invented by a single person but by this four‑member team; historically, Banting and Best are often highlighted in popular stories, while Macleod and Collip were crucial to the science and the drug’s final form.

In 1923, Banting and Macleod received the Nobel Prize in Physiology or Medicine for the discovery of insulin, and Banting later shared his prize money with Best while Macleod shared with Collip.

Tiny timeline

  • 1920: Banting reads an article about pancreatic cells and has the idea for a new way to extract the antidiabetic substance (later called insulin).
  • 1921: Banting and Best, in Macleod’s lab, perform dog experiments and isolate an extract that lowers blood sugar; Macleod names the substance “insulin.”
  • 1922: Collip’s purification allows the first successful human treatments, including 14‑year‑old Leonard Thompson, whose life is dramatically extended by insulin injections.

Since then, insulin has gone from animal extracts to modern human and analog insulins, but that original 1921–1922 breakthrough by Banting, Best, Macleod, and Collip is what people mean when they ask who “invented” insulin for diabetes.

Information gathered from public forums or data available on the internet and portrayed here.