Insulin
Insulin is a polypeptide hormone synthesized by the beta cells of the Islets of Langerhans within the pancreas. Insulin stimulates the cells of the body to take up glucose for cellular metabolism and storage. People who have an insulin deficiency develop the disease diabetes. Suffers either manifest insulin insensitivity where cells are rendered unresponsive to the hormone, or autoimmune destruction of the beta cells leading to decreased secretion of insulin.
Insulin that is administered in the treatment of diabetes is now made by biotechnology, by growing of human Insulin in a genetically modified, non-disease producing strain of Escherichia coli bacteria. This method creates an insulin with fewer impurities than the old method of extraction from Bovine (cow) or porcine (pig) pancreas.
Insulin was discovered by Canadian Fredrick Banting in 1921, and he would win the Nobel Prize, almost immediately afterwards in 1923.