Josef, Baron von Mering (February 28, 1849, in Cologne – January 5, 1908, at Halle an der Saale, Germany) was a German physician.
Working at the University of Strasbourg, Mering was the first person to discover (in conjunction with Oskar Minkowski) that one of the pancreatic functions is the production of insulin, a hormone which controls blood sugar levels.
Mering was curious about the pancreas, a comma shaped organ, that was situated between the stomach and the small intestine. In an effort to discover its function, he removed the organ from a dog. The dog was then noticed frequently urinating on the floor, although it was house trained. Mering realised that this was a symptom of diabetes and tested the urine, which was found to be high in sugar, confirming his suspicion.