Insulin was first used on a patient, 14-year-old Leonard Thompson, in Toronto on January 11, 1922, marking the beginning of effective diabetes treatment, with a refined, successful second injection on January 23, 1922, that stabilized his blood sugar. This breakthrough by Frederick Banting, Charles Best, and J.B. Collip transformed Type 1 diabetes from a death sentence into a manageable condition, saving millions of lives, notes the American Diabetes Association, History.com, and UMass Chan Medi