In 1923 the Nobel Prize in Medicine was awarded to Frederick Banting and John MacLeod for the discovery of insulin. It was actually a story of success that provoked a great scientific conflict.

Frederick Banting was a young Canadian surgeon, who was admitted into the laboratory of the eminent biochemist, interested in diabetes, Professor John Macleod, at the University of Toronto[13]. In 1920, Moses Barron, physician in Minnesota, published an article on “The relation of the islets of Langerhans to diabetes, with special reference to cases of pancreatic lithiasis[17] which was mentioning that the continuation of experiments of Minkowski and von Mering could lead to the discovery of a substance capable to control diabetes. Influenced by this article, Banting focused on the study of diabetes[13]. During that period the distinguished English physiologist Ernest Starling (1886-1927) was mentioning: “We don’t know yet how the pancreas affects sugar production or utilization in the same animal. It is generally assumed that it secretes into the bloodstream a hormone which may pass to the tissues and enable them to utilize sugar or pass to the liver and inhibit the sugar production of this organ… but we have been unable to imitate the action of the pancreas still in vascular connection with the body, by injection or administration of the extracts of this organ”[18].

On 16 May 1921, Banting started to collaborate with Charles Best, a young medical student. Experimenting in dogs they initially ligate the pancreatic ducts, achieving atrophy of the exocrine region and almost ten weeks later they removed dog’s degenerated pancreas. They crushed the atrophied pancreatic glands in a cool mortar and froze it in salt water. Then the mass was ground down and added to 100 mL of physiological salt. Afterwards, they administrated 5 mL of this extract intravenously to a depangreatized dog. Within 2 h its blood sugar had considerably dropped. They repeated several times the experiment with other diabetic dogs, gaining similar results and they experimented also with fetal calf pancreas using different ways of administration such as subcutaneous and rectal[19,20] (Figure ​(Figure44).

At the end of 1921 the skilled chemist James Collip joined the team and developed a better extraction and purification technique. Obtained substance was initially named by the team insletin and later on by MacLeod insulin[13].