The discovery of insulin as a hormone controlling glucose metabolism was first described and named by Sir Edward Albert Sharpey-Schafer in 1910. He identified that the pancreatic islets secrete a substance responsible for regulating blood sugar and coined the term "insulin" from the Latin word "insula" meaning "island," referring to the islets of Langerhans in the pancreas

. However, the actual isolation and extraction of insulin that led to its use as a treatment for diabetes occurred later, in 1921. This breakthrough was achieved by Dr. Frederick Banting, a Canadian surgeon, and Charles Best, a medical student, at the University of Toronto. They successfully isolated insulin from the pancreas of dogs and demonstrated its ability to lower blood glucose levels

. The purified form of insulin suitable for human use was developed with the help of biochemist James B. Collip. The first successful injection of insulin in a human patient, a 14-year-old boy named Leonard Thompson, took place in January 1922

. In summary:

• The concept and naming of insulin were introduced by Sir Edward Albert Sharpey-Schafer in 1910

• The actual discovery and isolation of insulin as a hormone for diabetes treatment were made by Frederick Banting and Charles Best in 1921, with purification by James B. Collip

• The first human treatment with insulin occurred in 1922

Banting and John Macleod received the Nobel Prize in Physiology or Medicine in 1923 for the discovery, which they shared with Best and Collip respectively