Who invented insulin medicine and when and purpose of this medicine?

Insulin is a hormone produced in the pancreas. It is released when blood sugar is too high (when blood sugar is too low, glucogen is released). It was isolated in 1921-22 at the University of Toronto. The scientists involved in the research were Dr. Fredrick Banting, Charles Bes, Professor J. J. R. Macleod and Dr. James Collip.