Insulin therapy-realising the potential.

Since its discovery in 1922, insulin has been the basis for treating diabetes both in patients with type I diabetes and those with type II diabetes when oral agents fail. For many years, commercial insulin production used animal sources and extracted insulin from bovine and porcine pancreas. While effective clinically, these insulin preparations also contained small amounts of impurities from other pancreatic components and were highly immunogenic. A significant development in insulin chemistry and the production process was the ability to produce pure animal insulin, allowing the introduction of a range of monocomponent insulins. From here, it was a logical step to the production of human insulin, initially by enzymatic modification of porcine insulin and then more generally by bacterial or yeast biosynthesis.