The sugar-regulating human hormone first isolated for medical use in the early 1920s was insulin. It is produced by beta cells in the pancreas and helps the body move glucose from the bloodstream into cells, where it can be used for energy or stored.
The breakthrough came at the University of Toronto. Frederick Banting proposed extracting the pancreas’s antidiabetic secretion, and medical student Charles Best helped conduct the early experiments. Biochemist James Collip then improved the purification process, making the extract suitable for human treatment. The first successful human treatment was given to Leonard Thompson, a 14-year-old with severe diabetes, in January 1922.
The discovery transformed type 1 diabetes from an almost universally fatal disease into a treatable condition. Banting and John Macleod received the 1923 Nobel Prize in Physiology or Medicine, sharing their prize money with Best and Collip. A useful historical distinction is that the research and initial isolation began in 1921, while 1922 marks the first successful human treatment and the start of insulin’s clinical era.