Short answers, pulled from the story.
Frederick Banting and Charles Best achieved the first successful isolation of insulin on the 30th of July 1921. This event occurred when they injected an extract from a dog's pancreas into another diabetic dog, causing its blood sugar to drop by 40% within one hour.
Leonard Thompson became the first human recipient of insulin on the 11th of January 1922 at Toronto General Hospital. The initial treatment caused a severe allergic reaction until biochemist James Collip purified the ox-pancreas extract over 12 days for a second dose on the 23rd of January.
Human insulin consists of 51 amino acids linked into two chains called the A-chain and the B-chain connected by disulfide bonds. Frederick Sanger sequenced this structure in 1951 making it the first protein fully mapped with additional intrachain bonds between positions A6 and A11.
Arthur Riggs and Keiichi Itakura produced the first genetically engineered recombinant human insulin in 1978 using E. coli bacteria. Genentech subsequently sold the first commercial biosynthetic version under the brand name Humulin in 1982 after Eli Lilly began producing large quantities by November 1922.
The World Health Organization added insulin to its model list of essential medicines in 2021. This decision recognized the critical importance of the hormone following decades of development from animal extracts to biosynthetic analogs like Humalog and Lantus.