In November of 1920, 29-year-old University of Toronto graduate and demonstrator at the University of Western Ontario, Frederick Grant Banting, met with John James Rickard Macleod, then a physiology professor at the university and international expert on diabetes and carbohydrate metabolism. Banting wanted to discuss a theory he had regarding the islets of Langerhans of the pancreas and whether they might give off an internal secretion somehow related to diabetes. Macleod encouraged Banting to explore this theory, but warned him that it would be at the expense of all his free time.
Macleod introduced Banting to two of his assistants, Charles Best and Clark Noble, both fourth-year students in the Honours Physiology and Biochemistry course. The two students flipped a coin to decide who would work with Banting on his research, leaving the future of their careers in the hands of luck. Banting and an auspicious Best were given a small, dilapidated laboratory in the physiology department and struggled with lack of funding and inadequate working conditions. Despite their circumstances and through numerous tests and considerable experimentation, Banting and Best were able to arrive at encouraging results in July of 1921 using a crude pancreatic extract that appeared to control blood sugar levels in diabetic dogs.
The first human recipient of the unpurified pancreatic extract, then called isletin, was a 14-year-old severely diabetic boy named Leonard Thompson. Thompson received an injection on January 11 and was observed to have a lowered blood sugar level as a result. While the trial was a success, the isletin needed to be purified before being considered a medical breakthrough. In December of 1921, Macleod introduced Dr. John B. Collip from the University of Alberta to Banting to help with the purification process of the isletin. Collip had extensive research experience and was responsible for making the crude pancreatic extract into what is now known as insulin. The isolation of the hormone, insulin, and its purification is a major breakthrough in the treatment of type 1 diabetes and its discovery is among one of the greatest medical achievements of the University of Toronto.
In 1923, Frederick Grant Banting and John James Rickard Macleod were honoured with the Nobel Prize in Physiology or Medicine. Both Banting and Macleod shared their prize winnings with Best and Collip, who were equally responsible for the medical breakthrough.