On the 11th January 1922, insulin was first used on a dying 14 year old boy called Leonard Thompson.

It was only semi successful because the purity of the Insulin was suspect.

Leonard suffered quite a severe allergic reaction to the insulin given to him, even though his blood sugar count dropped somewhat.

A man named James Collip worked for the next two weeks to purify the medicine, and on 23rd of January doctors again injected the boy Leonard with the medicine.

It was completely successful.