At the beginning of the 20th century, a diagnosis of Type 1 diabetes was a death sentence. Starvation diets were employed to delay the life-threatening symptoms of diabetes, but patient death was inevitable. Beginning on May 17, 1921, Frederick Banting and Charles Best, under the direction of J. J. R. Macleod, isolated what would later be known as insulin in a lab at the University of Toronto. Their extract was further purified and made safe for human injection by James Collip. Thirteen-year-old Leonard Thompson was selected to receive their first human trial, the results of which would go on to save the lives of millions around the world.