The history of insulin starts in 1889. At a congress in Heidelberg, the then 31-year old Oskar Minkowski reported on the results of experiments he and von Mering performed with dogs. They did pancreatectomies in dogs in order to study their digestion. However, one of their lab assistants noted an unexpected side-effect: the dogs started to suffer from polyuria. Well-aware that this was a symptom of diabetes in humans, Minkowski tested their urine for glucose and demonstrated that the dogs had indeed become diabetic. In subsequent experiments he ligated the ductus pancreaticus, performed subtotal pancreatectomies, and performed pancreas transplants, all of which led to the conclusion that the pancreas had to produce a hormone that was released in the blood and that influenced glucose levels.
In the years after Minkowski's initial report, researchers across the world tried to isolate this elusive pancreatic hormone. However, suppletion of patients with all kinds of pancreatic extracts failed to produce the wanted results.
It was only in 1921 that Frederick Banting and Charles Best, who worked under Collip and John Macleod in Toronto, succeeded in extracting the pancreatic hormone.
The hormone was given the name insulin (at the suggestion of Sir Edward Sharpey-Schafer) to mark the fact that it was produced in the pancreatic islets. The first patient treated was a 14-year old boy named Leonard Thompson who was in diabetic coma and made a remarkable recovery. In 1923 Banting and MacLeod received the Nobel Prize for their discovery and Banting was named Time's 'Man of the year'.