On 11 January 1922, in a Toronto hospital ward, a skinny fourteen-year-old boy named Leonard Thompson lay in a metal bed weighing only 65 pounds. He had type 1 diabetes, and back then that was a death sentence. Doctors had tried everything - even starvation diets that left children eating almost nothing for months. Leonard was so weak his hair was falling out. The doctors gave him a few weeks at most. Then they pulled out a small bottle of brown, murky liquid and gave him an injection.
The liquid was called insulin. It had been extracted from cattle by a young Canadian surgeon named Frederick Banting and a medical student named Charles Best, in a hot summer lab where they sometimes slept on the floor. The first batch given to Leonard was impure and barely worked. But a chemist named James Collip cleaned it up, and a second dose 12 days later brought Leonard back to life. His blood sugar dropped. He started eating. He gained weight. He went home.
That one injection cracked the door open for millions. Today around 9 million people worldwide depend on insulin every single day to manage type 1 diabetes, and many more use it for type 2. Banting and another scientist, John Macleod, won the Nobel Prize the next year. Banting refused to patent the discovery, selling the rights to the University of Toronto for just one dollar - because he wanted the medicine to belong to the whole world, not to him.
