John James Rickard Macleod was a Scottish physiologist who shared the 1923 Nobel Prize for Physiology or Medicine with Frederick Banting.
He is known for being a pioneer in the discovery of insulin, and it was in his laboratory at the University of Toronto that Banting and Charles Best succeeded in isolating and preparing insulin for mass use.
Macleod’s early education was in Aberdee, where he studied medicine at the Marischal College of the University of Aberdeen. He moved to the United States in 1903 to become a Professor of Physiology at the Western Reserve University at Cleveland, Ohio.
In 1918, Macleod was elected Professor of Physiology at the University of Toronto, Canada. He served as Director of the Physiological Laboratory and Associate Dean of the Faculty of Medicine, and it was during his time in Toronto that he met Banting and Best.
MacLeod was director of the laboratory Banting and Best worked in. After being awarded the Nobel Prize, Banting and MacLeod decided to share the prize with the entire team who weren’t recognised by the Nobel committee.
MacLeod was also renowned for his work on carbohydrate metabolism, especially in diabetes. He had 37 papers published on carbohydrate metabolism and 12 papers on experimentally produced glycosuria (when excess glucose is removed from the blood by the kidneys and excreted via the urine).
He returned to Scotland in 1928 to become Professor of Physiology and later Dean of the University of Aberdeen Medical Faculty. MacLeod decided to stop working on insulin, and went on to prove that the central nervous system plays an important role in maintaining carbohydrate metabolism balance.
He remained active as a teacher, researcher and author of 11 books, including Practical Physiology (1902) and Physiology and Biochemistry in Modern Medicine (1918).
MacLeod died in 1935 in Aberdeen.