Insulin: A History of Diabetes Care
Say the word “insulin” and most people have a flash of hypodermic needles. Perhaps they know someone with diabetes who has to inject this hormone every day to stay healthy, or they have seen it used in medical shows on TV.
Insulin is a hormone, a chemical substance produced by the body to act as a “messenger” in the bloodstream to make sure certain processes occur. It is manufactured in the Islets of Langerhans in the pancreas, a medium sized gland that sits just below the stomach. One of insulin’s most important jobs is to make sure the body’s tissue cells take up glucose from the blood and store it so they have a supply of fuel when they need to grow, repair, or take part in activity.
In Type I diabetic people the pancreas may have suffered damage so that it no longer produces enough insulin, while inType II diabetics the insulin may be produced but the cells have ceased responding to its message. In either case, the glucose in the blood, derived from the digestion of carbohydrates and sugars in the stomach, builds until it reaches a level that is toxic for the organs. If treatment is not received, a diabetic coma and even death may be the result.
Insulin was first isolated in 1916 by Professor Nicolae Paulescu at the University of Bucharest. Previous to that, experiments on dogs had suggested its existence to the scientists Oskar Minkowski and Joseph von Mering at Strasbourg University. They removed the pancreas from dogs and found this caused diabetic symptoms and that flies were attracted to the animals’ urine, which was found to be full of sugar. An American medical student, Eugene Opie, had already made the connection between the islets of Langerhans in the pancreas and diabetes. The name “insulin” comes from the Latin word for islands, the name given to the tissues in the pancreas by their discoverer Paul Langerhans in 1869.
Paulescu’s work was replicated in 1923 by Canadian doctor Frederick Banting and biochemist John McLeod, who later won the Nobel prize for their work. These men also used dogs as test subjects, and Banting kept one female dog, in which he had surgically disabled the pancreas, alive for several weeks by giving her extracts taken from pancreatic tissue. The scene was set for the medical developments which would bring life and hope for millions of diabetics.
Banting used insulin derived from a fetal calf to save a teenage boy named Leonard Thompson who was dying from type I diabetes in a Toronto hospital. First trials were not a success, as the extract caused Leonard to have an allergic reaction, but 12 days later a purer dose was injected and Leonard recovered. He received insulin injections for the rest of his life, and died from a different cause.
Insulin from cattle was used for many years to treat diabetics, as it is very similar to human insulin, but impurities often caused problems such as allergic response in patients. A breakthrough occurred in the 1960s when synthetic insulin was manufactured, and this is now used universally.
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