On January 11, 1922, insulin was used for the first time to treat a person with diabetes. Leonard Thompson was a fourteen-year-old young man that was dying from type 1 diabetes. On January 11, he was injected with insulin for the first time. Within twenty-four hours, his dangerously high blood sugar levels dropped. However, he had developed an abscess at the injection site and still had high levels of ketones.
The inventor of insulin, Collip, worked non-stop to purify the solution even further. Leonard was given a second injection on January 23, this time, it was successful. For the first time, diabetes was not a death sentence.