Molecular structure model of insulin, c 1965.
© Science Museum / Science & Society Picture Library
Insulin is a protein hormone produced in the pancreas, which regulates the metabolism of glucose, fats and proteins. It was discovered in 1921 by the Canadian physician Frederick Banting (1891-1941), who pioneered the use of insulin for the treatment of diabetes. Insulin was the first protein to have its molecular structure completely established, by X-ray crystallographer Dorothy Hodgkin (1910-1994) in 1969. It consists of two peptide chains linked together by two disulphide bridges.