Let me remind you a short story of insulin. Full story you can read here in the article “What Is Insulin?”
Sugar diabetes disease was known to humanity from ancient times, but no real progress in treatment was made until German physiologists Joseph vom Mering and Oskar Minkowski discovered in 1889 by accident that the pancreas was central to diabetes. That discovery was a pivotal point in sugar diabetes management and treatment. While studying digestion in a laboratory dog, two collegues removed the pancreas to sec the effect on digestion. The dog started urinating more often than usual and the doctors had good judgement to test the urine for sugar. True enough, the dog developed sugar diabetes without the pancreas.