Insulin was discovered by Sir Frederick G Banting (pictured), Charles H Best and JJR Macleod at the University of Toronto in 1921 and it was subsequently purified by James B Collip.
Before 1921, it was exceptional for people with Type 1 diabetes to live more than a year or two. One of the twentieth century’s greatest medical discoveries, it remains the only effective treatment for people with Type 1 diabetes today.
On 11 January 1922, Leonard Thompson, a 14-year-old boy with diabetes, who lay dying at the Toronto General Hospital, was given the first injection of insulin. However, the extract was so impure that Thompson suffered a severe allergic reaction, and further injections were cancelled.
Over the next 12 days, James Collip worked day and night to improve the ox-pancreas extract, and a second dose was injected on the 23 January. This was completely successful, not only in having no obvious side-effects, but in completely eliminating the glycosuria sign of diabetes.