Insulin was discovered in 1921 at the University of Toronto by a team consisting of Sir Frederick G. Banting, Charles H. Best, and John J.R. Macleod. Banting, a Canadian surgeon, initially conceived the idea and worked with Best, a medical student, to isolate insulin from the pancreas of dogs. Macleod provided laboratory space and guidance. Later, James B. Collip helped purify the insulin extract to make it suitable for human use
. The first successful treatment of a human with insulin was in January 1922, when 14-year-old Leonard Thompson, who was dying from type 1 diabetes, received an insulin injection that significantly lowered his blood sugar levels
. In 1923, Banting and Macleod were awarded the Nobel Prize in Physiology or Medicine for the discovery of insulin. Banting shared his prize money with Best in recognition of his contribution
. While Banting, Best, Macleod, and Collip are credited with the discovery and development of insulin as a treatment, earlier researchers such as Sir Edward Albert Sharpey-Schafer had identified the pancreatic "islets" and hypothesized the existence of a chemical (which he named insulin) responsible for glucose regulation. Other scientists like Eugène Gley and Nicolae Paulescu also made important but less recognized contributions to the understanding of insulin
. In summary, insulin was discovered by Frederick Banting, Charles Best, and John Macleod in 1921, with purification by James Collip, marking a major medical breakthrough that transformed diabetes from a fatal disease to a manageable condition
