January 11, 1922, etched itself into medical lore when 14-year-old Leonard Thompson survived what should have been his last days thanks to insulin. In Toronto, this injection didn’t just save one life—it redefined diabetes treatment for humanity.
Type 1 diabetes in the early 20th century meant slow starvation. Diets limited to 500 calories daily couldn’t halt the pancreas’s failure to produce blood-sugar regulators. Thompson, emaciated and critical, was the perfect candidate for an experimental hormone painstakingly refined by University of Toronto scientists Frederick Banting, Charles Best, James Collip, and John Macleod.
Extracted from dog pancreases initially, insulin faced purity hurdles. The debut dose caused abscesses, but Collip’s purification miracle followed. Thompson’s blood sugar plummeted to normal, appetite surged, and weight climbed—miracles in days.
Commercial rollout followed swiftly, with Eli Lilly scaling production. Diabetes mortality plunged; life expectancy soared. This wasn’t mere science; it was compassion weaponized against disease. Over 100 years on, insulin evolves, but its origin story fuels ongoing quests for cures.