The Discovery of Insulin: 1921
1921 · event
In the summer of 1921, in a modest laboratory at the University of Toronto, Frederick Banting and Charles Best embarked upon an experiment born of desperation and insight. Banting, a young surgeon with limited research experience, had conceived a radical idea: that by tying off the pancreatic ducts of dogs, they might isolate the elusive internal secretion that controlled blood sugar. While others had pursued this phantom for decades, Banting possessed an intensity of purpose that would not be denied. He and his eager assistant Best, barely more than a student, worked through the sweltering summer, extracting a murky brown liquid from the damaged glands of their animal subjects. This crude preparation, which they named "isletin," seemed to work-when injected into diabetic dogs, their blood sugar fell and their symptoms improved.
The implications were staggering, yet the path ahead remained treacherous. The extract was unstable, contaminated, and unreliable, and animal experiments could not guarantee success in humans. Nevertheless, by January 1922, their work had matured enough to attempt the first injection into Leonard Thompson, a fourteen-year-old boy wasting away from diabetes at Toronto General Hospital. The initial trial brought modest improvement; subsequent injections, refined by colleague James Collip's purification methods, transformed the boy's condition dramatically. Thompson regained weight, energy flooded back into his failing body, and the shadow of death receded.
Word spread rapidly through the medical world like dawn breaking over dark water. Here at last was not merely a treatment but a resurrection-a hormone that could restore life to those whom the disease had sentenced to slow extinction. Within months, pharmaceutical companies were racing to produce insulin at scale, and diabetics everywhere began to emerge from the twilight of their condition. Banting and Best's discovery would define the twentieth century's relationship with chronic illness, transforming what had been a death sentence into a manageable condition, and securing their place in humanity's debt.