a hormone required by cells in order for
them to remove and use glucose from the blood
secreted by areas within the pancreas known as
Islets of Langerhans. Although the level of
insulin in the body is supposed to be fairly
constant, such is not the case in people who
suffer from diabetes, and those who have diabetes
often have to get their insulin from shots.
Insulin was the first hormone
ever identified, by Frederick Banting and Charles Best in the early 1920's.
Banting and Best tied string around the
pancreatic duct of several dogs; when the
pancreases were examined later, all of the
pancreas digestive cells were either dead or
absorbed by the immune system, leaving only
thousands of pancreatic islets behind. The men
then isolated the protein from the islets and
In 1922, Banting and Best
perfected a method for extracting insulin from
cattle and pig pancreases, and their method
remains the most commonly used one today.
However, some diabetics do not respond well to
non-human insulin, and for these patients insulin
that has been genetically reproduced (using a
process approved by the FDA in 1982) is used.
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