Explanation:

• Canadian physician Frederick Banting and medical student Charles H. Best discovered the hormone insulin in pancreatic extracts of dogs. On July 30, 1921, they injected the hormone into a diabetic dog and found that it effectively lowered the dog’s blood glucose levels to normal.
• By the end of that year, with the help of Canadian chemist James B. Collip and Scottish physiologist J.J.R. Macleod, Banting and Best purified insulin, and the next year it was used to successfully treat a boy suffering from severe diabetes.
• The researchers were celebrated and honored for their breakthrough. Banting and MacLeod even shared the 1923 Nobel Prize for Physiology and Medicine for their work.