However in 1889, a simple experiment performed by Oskar Minkowski revolutionized the understanding of the pancreas’s function.
Oskar Minkowski was from a family of scholars. His younger brother Hermann was a professor of mathematics, who had Albert Einstein as a student. Hermann Minkowski developed a description of space-time which is a convenient representation of Einstein’s Theory of Special Relativity. Oskar’s son, Rudolph Minkowski, became a well-known astrophysicist. Rudolph first identified a dim star in the Crab Nebula as the source of the supernova remnant. This star later became known as the Crab Pulsar.
Oskar Minkowski’s simple experiment was to completely remove the pancreas from a dog and measure the sugar levels of the dog’s urine. While the concept was simple, the execution was not. It was easy to leave a small remnant of the pancreas behind, confusing the interpretation of the results. Once Minkowski showed that the complete removal of the pancreas led to diabetes in a dog, the experiment was repeated in cats and other mammals and always led to diabetes.
Minkowski was known for his careful work as an experimenter and surgeon. After removal of the dog’s pancreas, the dog initially looked normal. However, upon close review Minkowski noted that the dog had symptoms consistent with diabetes: unquenchionable thirst and constant urination. When he tested the glucose levels of the dog, he confirmed the diagnosis of diabetes.
He described his discovery in a 1926 letter this way,
That same afternoon in Naunyn’s laboratory, with von Mering’s help, I took out his dog’s pancreas. Perhaps, as a lucky coincidence, that particular animal possessed especially favorable anatomical conditions; they vary considerably in different animals. The whole gland was removed and the abdominal wall sutured; the animal remained alive and apparently well for nearly four weeks. I intended to return it to von Mering for his experiments on the utilization of fats, so I did not bother much about it; but because there was no suitable cage available it was kept tied up in one part of the laboratory. The day after the operation, von Mering had to go to Colmar urgently because his father in law was seriously ill with pneumonia. He had to stay there over a week. Meanwhile the dog, which was house trained, very often micturated in the laboratory. I scolded the servant for not letting it out frequently enough, but he said: “I do, but the animal is queer; as soon as it comes back it passes water again even if it has just done outside.”
This observation induced me to collect some of the urine in a pipette and do a Trommer’s test. Finding the urine reduced strongly, I made a 10 per cent solution with 1.5 cc I still had in the pipette and found it contained 12 per cent sugar.
I thought at first that the glycosuria might be due to the act that von Mering had treated his dog for a long time with phloridzin. So I immediately pancreatectomized three more dogs with no sugar in their urine previous to the operation. The second and third animals died two days later of necrosis of the duodenum, but both had glycosuria before they died. The fourth animal survived and from the second day after pancreatectomy had a persistent diabetes just like the first animals. [From The discovery of pancreatic diabetes; the role of Oscar Minkowski.]
The identification of an animal model for a disease is the first foothold for curing the disease. Minkowski’s work was widely known in the scientific community and easily replicated by others. The old thought, that the pancreas had no function like the appendix, was tossed. The new thought was that the pancreas produced some secretion that prevented diabetes.