On January 11, 1922, the first injection of insulin was given to a 14-year-old diabetic patient.
At the end of the 19th century, the scientist Paul Langerhans identified previously unnoticed groups of cells in the pancreas, later named after him "islets of Langerhans". Later physicians Oskar Minkowski and Joseph von Mering demonstrated that dogs with pancreas removed develop diabetes. When the dog was given a pancreatic extract, the blood sugar level decreased, and the symptoms of diabetes mellitus disappeared. It was concluded that the pancreas is somehow responsible for maintaining normal blood sugar levels. However, the mechanism remained unclear and further studies were needed.
At the beginning of the 20th century, L.V. Sobolev found out that after pancreatic ducts ligation, unlike the atrophied exocrine pancreas, the islets remain intact, and diabetes does not develop. These results, along with the well-known fact of changes in islets of diabetic patients allowed to conclude that the pancreatic islets are necessary for carbohydrate metabolism regulation. Many scientists from around the world attempted to isolate the secret of pancreatic islets and find a way to treat diabetes. In the end, scientists from the University of Toronto succeeded. Dr. Frederick Banting and his young assistant, Ph.D. student Charles Best, studied pancreatic extract in search of a substance that is responsible for glucose utilization. Their hard work was crowned with success in the summer of 1921 - insulin was obtained. The first patient to receive an injection of the new substance was 14-year-old Leonard Thompson, suffering from a severe form of diabetes. After several insulin injections, the patient felt better, and after six months of treatment, he returned to normal life. The news of the first clinical trial of insulin by Frederick Banting and his colleague Charles Best became an international sensation. At the end of 1922, insulin was introduced to the market. The discovery of insulin saved millions of lives, and while diabetes is still a chronic disease, people can control it now.