Essential Contributions of Pathologists and Laboratory Physicians Leading to the Discovery of Insulin.

CONTEXT.— Frederick Banting, Charles Best, J. Bertrand Collip, and J. J. R. Macleod contributed to the discovery of insulin in 1921-1922. Recent advances in anatomic pathology, experimental pathology, and clinical pathology were necessary for the research in Toronto, Ontario, Canada, to begin and to succeed. OBJECTIVE.— To explore the role of pathology and laboratory medicine in laying the foundation for the discovery of insulin. DESIGN.— Available primary and secondary historical sources were reviewed. RESULTS.— During a 3-decade period, pathologists, through autopsy pathology and experimental animal studies, were able to provide solid evidence that the pancreatic islets were the source of the internal secretion responsible for proper carbohydrate metabolism. Banting, a surgeon with no previous research experience, read about these studies in a case report with an extensive literature review by pathologist Moses Barron; this piqued Banting's interest and caused him to approach Macleod, a Toronto physiology professor, with an idea that initiated the research. Advances in clinical laboratory medicine, which allowed them to measure blood glucose levels using small blood volumes, were critical to their success. CONCLUSIONS.— By 1921-1922, the pieces necessary to solve the puzzle were available. The primary reason that the time was ripe for the discovery was because of the contributions of pathologists and laboratory physicians in the preceding 3 decades. As the 100th anniversary approaches, our profession can take pride in its important contributions to the discovery of insulin, which is broadly recognized as one of the most important medical research advances of the 20th century.