Lat. “insula” = island

So called because the hormone is secreted by the islets of Langerhans in the pancreas. The first human trial of insulin, extracted using dog pancreas, was conducted in January 1922 on 14-year-old Leonard Thompson, a boy with severe diabetes.

To date, insulin has saved the life of millions of patients, making it one of the most important drugs in history.

The discovery of insulin in 1921 stands as a landmark achievement in medical history, transforming the treatment of diabetes mellitus. This breakthrough was the culmination of years of research and experimentation, with the contributions of several individuals playing crucial roles.

In 1889, two German researchers, Oskar Minkowski and Joseph von Mering, made a serendipitous observation that would set the stage for insulin’s discovery. They removed the pancreas from dogs, leading to the development of hyperglycemia, or high blood sugar levels, a hallmark symptom of diabetes. This observation suggested that the pancreas played a role in regulating blood sugar, and subsequent research focused on identifying the specific substance responsible for this function.

In 1908, Eugene Gley, a French physiologist, proposed the concept of an “internal secretion” produced by the pancreas, which he called “isletin.” This term reflected the specialized clusters of cells within the pancreas, known as the islets of Langerhans, which are responsible for insulin production.

In 1921, Frederick Banting, a young surgeon working at the University of Toronto, embarked on a quest to isolate insulin. Inspired by Gley’s work, Banting proposed a bold idea: to remove the pancreas from dogs and then extract the active substance from the remaining pancreatic tissue. He partnered with Charles Best, a medical student, and together they embarked on this ambitious experiment.

Banting and Best’s early attempts to extract insulin were unsuccessful due to the complex nature of the pancreatic tissue and the presence of impurities in their preparations. However, their persistence paid off when they discovered that duct ligation, a procedure that blocked the pancreatic duct, could preserve the islets of Langerhans, allowing them to selectively extract insulin.

To further purify their extract, Banting and Best collaborated with James Collip, a biochemist, who developed techniques to isolate a more refined form of insulin. In January 1922, the first human trial of insulin was conducted on 14-year-old Leonard Thompson, a boy with severe diabetes. The results were remarkable: Thompson’s blood sugar levels plummeted, and he experienced a dramatic improvement in his condition.

The discovery of insulin was a turning point in the treatment of diabetes, providing a life-saving therapy for millions of people worldwide. It ushered in a new era of medical research and treatment, paving the way for further advancements in diabetes management.