Leonard Thompson was the first patient to receive insulin injections, in January 1922.

Before insulin, diabetes was a terminal disease. Diabetic patients like Thompson had few effective treatments. A strict diet was one of the few options that could keep patients alive.

Aged just 14, the Canadian patient had been diabetic for three years. Thompson’s condition worsened during 1921 - he was admitted to Toronto General Hospital weighing only about 65 pounds. He was close to slipping into a diabetic coma and would soon die.

Thompson’s father let the hospital try Banting and Best’s new pancreatic extract for the first time. However, the extract was an impure form of insulin. Thompson had an allergic reaction, and it had little effect.

A few days later Thompson was injected with a purer form of insulin. This was extracted by the chemist James Collip. Thompson’s blood sugars gradually returned to normal and his diabetic symptoms began to disappear. News of Thompson’s recovery spread, inspiring people with diabetes and their families to write letters to Banting and Best asking for urgent treatment.

Thompson lived another 13 years using insulin. When he was 27 he died of pneumonia - thought to be a complication of his diabetes.