Medications

What is synthetically manufactured insulin?
Answered by Craig C. Freudenrich and Science Channel
  • Craig C. Freudenrich

    Craig C. Freudenrich

  • Science Channel

    Science Channel

  1. Diabetes is a devastating disease in which a person's blood sugar levels are abnormally high. The consequences include weight loss, dehydration, kidney disease, blindness, gangrene, coma and death. Before 1920, scientists knew that there was a connection between the pancreas and diabetes. The pancreas of people with diabetes often was damaged, specifically an area called the islets of Langerhans. If researchers removed the pancreas from animals, the animals developed diabetes. If the pancreatic duct was tied off, the animal developed digestive problems, but no diabetes. It became clear that the pancreas produced some substance that regulated blood sugar.

    In 1920, Frederick Banting convinced John Macleod, the chairman of physiology at the University of Toronto, to provide him with lab space and an assistant (medical student John Best), so that he could try to isolate the substance from the islets of Langerhans. In 1921, Banting and Best made extracts from the islets that lowered blood sugar in diabetic dogs. Macleod assigned chemist James Bertram Collip to help purify the substance called insulin from the extracts. The work of the researchers succeeded in 1922; they tested the purified extract on a boy with diabetes named Leonard Thompson. Thompson's blood sugar lowered and he improved. Banting and Macleod were awarded the Nobel Prize in 1923 for their work. Banting was outraged that Best was not named to share the prize [source: NobelPrize.org]. Banting shared his portion of the prize money with Best, and Macleod subsequently shared his with Collip.

    Once insulin was discovered, scientists at Eli Lilly purified it from pancreases of animals such as cows and pigs, and mass produced insulin. One drawback was that the animal insulin caused allergic reactions in patients. In 1951, Fred Sanger discovered the amino acid sequence of cow insulin. This discovery led to the production of insulin made from chemicals between 1966 and 1975 when Ciba-Geigy scientists made the first fully synthetic molecule. In 1978, scientists at Genentech cloned the human gene for insulin and placed it in E.coli bacteria. They grew vast quantities of the bacteria, which began making human insulin. They harvested the bacteria and purified the human insulin protein. Subsequent clinical trials showed that recombinant human insulin was effective in controlling diabetes [source: History of Insulin]. Genentech licensed the process to make this recombinant insulin to Eli Lilly. Since 1982, Lilly has produced recombinant human insulin for treating people with diabetes.

    Injecting insulin
    (iStockphoto.com/Andrzej Tokarski)

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  2. Synthetically manufactured insulin, also called recombinant DNA insulin, is derived using the gene for human insulin, in an innovative process developed by the biotechnology company Genentech in 1978. Synthetically manufactured insulin was a key breakthrough, because it did not cause the allergic reaction that animal insulin caused in some people. The synthetic insulin could be produced in large quantities, and it became commercially available in the early 1980s. Almost all type l diabetics today who use insulin use recombinant DNA insulin.

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