John Macleod – Facts
The Nobel Prize in Physiology or Medicine 1923 was awarded jointly to Frederick Grant Banting and John James Rickard Macleod "for the discovery of insulin"
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NobelPrize.org
John James Rickard Macleod

The Nobel Prize in Physiology or Medicine 1923

Affiliation at the time of the award: University of Toronto, Toronto, Canada

Prize motivation: “for the discovery of insulin”

Prize share: 1/2

Work

Diabetes is the body's inability to metabolize sugar correctly. Doctors realized that diabetes is caused by a lack of insulin, which is formed in parts of the pancreas, but could not prove it. Frederick Banting suspected that another substance formed in the pancreas, trypsin, broke down the insulin. In John MacLeod's laboratory in 1921, Frederick Banting and Charles Best treated dogs so that they no longer produced trypsin. Insulin could then be extracted and used to treat diabetes.