Frederick G. Banting and John J.R. Their work helped establish insulin as a treatment for diabetes, a disease that, in its severe forms, had often been fatal before insulin therapy became available.
Macleod were awarded the 1923 Nobel Prize in Physiology or Medicine for the discovery of insulin, a hormone that regulates blood glucose levels.
Diabetes had been linked to the pancreas decades before insulin was isolated. Subsequent research established the importance of the islets of Langerhans, clusters of cells within the pancreas, in regulating blood sugar. Frederick G. Banting was a Canadian physician and surgeon whose interest in diabetes led him to investigate the role of the pancreas in regulating blood glucose. After serving in the First World War, he returned to Canada and worked in medical practice before pursuing research. Macleod provided laboratory facilities, scientific guidance and access to experimental animals. Banting began the work with Charles Best, a medical student who assisted with the experiments. Their collaboration brought together Banting’s research hypothesis and Macleod’s experience in physiology, setting the stage for the experiments that led to the development of insulin as a treatment for diabetes. The researchers tied off the pancreatic ducts of dogs, allowing the enzyme-producing tissue to degenerate while attempting to preserve the islets. They prepared extracts from the pancreas and tested them in dogs whose pancreases had been removed. The extracts lowered blood sugar and improved the animals’ clinical condition. The first injection produced limited results, and an abscess developed at the injection site. After the preparation was further purified, a second course of treatment produced a marked improvement in his condition, with a substantial reduction in blood glucose and urinary glucose. Thompson’s response demonstrated that insulin could be used to treat diabetes in humans. The development of more reliable preparations and the expansion of production subsequently allowed treatment to reach more patients. Insulin did not cure diabetes, but it changed the outlook for people living with the disease. Before its introduction, severe diabetes was often managed through restrictive diets that could prolong life only for a limited period. Insulin enabled patients to use glucose more effectively and helped prevent the severe metabolic disturbances associated with insulin deficiency.
In 1889, researchers Oskar Minkowski and Joseph von Mering demonstrated that removing the pancreas from dogs produced diabetes. Banting approached Macleod in 1921 with a proposal to isolate a substance from the pancreas that could regulate blood glucose. In January 1922, insulin was administered to Leonard Thompson, a 14-year-old boy with severe diabetes, at Toronto General Hospital.
