On this day 103 years ago, on January 11, 1922 (December 14, 1921 lunar calendar), Dr. Banting, a Canadian doctor, first used insulin to treat diabetes. On January 11, 1922, Dr. Banting, a doctor at Toronto General Hospital in Canada, first used insulin to treat diabetes. 14-year-old Leonard Thompson was almost on the verge of death when he was admitted to the hospital. After receiving insulin, his condition improved significantly and he finally lived to the age of 35.