Frederick Banting, Charles Best, James Collip, and John Macleod

On July 27, 1921, Frederick Banting and Charles Best isolated insulin at the University of Toronto. An excerpt from the article:

"In the early 1920s Frederick Banting and Charles Best discovered insulin under the directorship of John Macleod at the University of Toronto. With the help of James Collip insulin was purified, making it available for the successful treatment of diabetes. Banting and Macleod earned a Nobel Prize for their work in 1923.

At the turn of the 20th century a strict low-calorie, no-carbohydrate diet was the only effective treatment for diabetes. But this method, with food intake sometimes as low as 500 calories per day, had its consequences, as slow starvation, like diabetes, drained patients of their strength and energy, leaving them semi-invalids. The diet treatment also required an inordinate amount of willpower on the part of the patient, very few of whom were able to maintain low-calorie diets over the long term. In 1921 researchers at the University of Toronto began a series of experiments that would ultimately lead to the isolation and commercial production of insulin—a pancreatic hormone essential for metabolizing carbohydrates—and the successful treatment of diabetes."