First Successful Insulin Treatment for Diabetes

Context

Diabetes mellitus had been recognized for millennia as a wasting disease that led to death, often within months of onset in its severe form. By the early twentieth century, physicians understood that the pancreas played a central role, yet attempts to extract a therapeutic substance from the organ had repeatedly failed due to impurities and digestive enzymes that destroyed the active principle. Strict low-carbohydrate diets could extend life for a short time but left patients severely malnourished and offered no cure.

What Happened

At the University of Toronto, orthopedic surgeon Frederick Banting and medical student Charles Best had isolated insulin from dog pancreases in the summer of 1921 under the supervision of professor J.J.R. Macleod. Biochemist James Collip joined the team to purify the extract. On January 11, 1922, fourteen-year-old Leonard Thompson, who had been diagnosed with type 1 diabetes and weighed roughly sixty-five pounds while slipping in and out of coma, became the first patient to receive the preparation at Toronto General Hospital. The initial dose lowered his blood sugar but triggered an allergic reaction because of residual impurities.

Aftermath

Collip quickly developed a more refined purification process. On January 23, 1922, Thompson received a second series of injections that stabilized his blood sugar without adverse effects and allowed rapid clinical improvement. The University of Toronto secured patents on the extraction method and assigned them to the institution for one dollar each, enabling royalty-free licensing to manufacturers. Insulin became commercially available within months.

Legacy

The discovery converted type 1 diabetes from an immediate death sentence into a manageable chronic illness, ultimately saving millions of lives worldwide. Banting and Macleod received the 1923 Nobel Prize in Physiology or Medicine for the work, which also established foundational methods for hormone isolation and replacement therapy while modeling large-scale collaborative medical research conducted without commercial restriction on the core discovery.