Minkowski worked with Josef von Mering on the study of diabetes at the University of Strasbourg.
Their landmark study in 1889 in dogs induced diabetes by removing their pancreas.
It was Minkowski who performed the operation and made the crucial link to recognize that the symptoms of the treated dogs were due to diabetes.
Thus they were able to indicate that the pancreas contained regulators to control blood sugar; they also provided a model for the study of diabetes.
Their work led other doctors and scientists to pursue further research on the relation of the pancreas to diabetes, and ultimately resulted in the discovery of insulin as a treatment for the disease.

Joseph von Mering, Oskar Minkowski: Diabetes mellitus nach Pankreasextirpation.
Centralblatt für klinische Medicin, Leipzig, 1889, 10 (23): 393–394.
Archiv für experimentelle Patholgie und Pharmakologie, Leipzig, 1890, 26: 37.
It begins with, After removal of the pancreas dogs get diabetes.
It starts sometime after the operation and will persist for weeks continuously until their death...
Minkowski worked with Josef von Mering on the study of diabetes at the University of Strasbourg. Their landmark study in 1889 in dogs induced diabetes by removing their pancreas. It was Minkowski who performed the operation and made the crucial link to recognize that the symptoms of the treated dogs were due to diabetes. Thus they were able to indicate that the pancreas contained regulators to control blood sugar; they also provided a model for the study of diabetes. Their work led other doctors and scientists to pursue further research on the relation of the pancreas to diabetes, and ultimately resulted in the discovery of insulin as a treatment for the disease.
Joseph von Mering, Oskar Minkowski: Diabetes mellitus nach Pankreasextirpation. Centralblatt für klinische Medicin, Leipzig, 1889, 10 (23): 393–394. Archiv für experimentelle Patholgie und Pharmakologie, Leipzig, 1890, 26: 37. It begins with, After removal of the pancreas dogs get diabetes. It starts sometime after the operation and will persist for weeks continuously until their death...
Oskar Minkowski