Although diabetes mellitus has been known since Egyptian times, very little treatment existed until the early 1920's. Historically, diabetic patients were put on a starvation diet, essentially limiting carbohydrates and sugar. This diet would avoid a spike in blood sugar. There was little the medical profession could offer patients. Most diabetics died young.
In 1921 Fredrick Banting and Charles Best (working under the supervision of professor John MaCleod of the university of Toronto made a pancreatic extract from one dog and injected it into another dog which had had its pancreas removed. This extract reduced the high sugar level in the blood of the diabetic dog. This insulin extract was tested later on humans and similar results were obtained. (9)
The success of this treatment resulted in the awarding of the Nobel Prize in medicine to Fredrick Banting and John MaCleod in 1923 (Banting shared part of his prize money with Charles Best). They made the patent for insulin available, and so insulin production was available worldwide.
In 1955, insulin was the first protein to be sequenced by British biochemist Fredrick Sanger, for which he won the Nobel Prize in Chemistry. Three years later it was the first protein to be chemically synthesized.
In the early days (1920-1982) insulin extracts from cows and pigs provided insulin to millions of people suffering from diabetes. As this insulin is not genetically identical to human insulin, it caused side effects in some patients. In 1982 recombinant DNA technology allowed
E. coli
bacteria to be genetically engineered to produce human insulin. Insulin is now molecularly exact, and diabetics suffer no immunogenic side effects.