Insulin (1921)

Frederick Banting and Charles Best's isolation of insulin at the University of Toronto in 1921 transformed Type 1 diabetes from a death sentence — patients typically died within years of diagnosis — to a manageable chronic condition. Before insulin, the only treatment was a near-starvation diet that might extend life by a year. The first human recipient in January 1922 was a 14-year-old boy in a diabetic coma who made a complete recovery.