Before the discovery of insulin, diabetes was a death sentence. Widely regarded as the first true miracle drug, insulin has saved millions of lives. But why do some people need insulin and how does it work?
Diabetes has been recognised as a disease since ancient times, and as early as 1775 physician Matthew Dobson detected the presence of sugar in the urine of diabetics. Diabetic children were thin, listless and pale, with sickly sweet breath, and would inevitably slip into a coma before their untimely death.
In 1797, John Rollo demonstrated that a very low kilojoule diet could prolong the lives of diabetics, but only for a limited period before they died of starvation or complications from malnutrition.
But at the beginning of the 20th century, although the biological mechanism of diabetes was understood, medical science was yet to come up with an effective treatment.
Type 1 Diabetes
Diabetics were suffering from what is now known as type 1 diabetes. This means the body cannot make insulin, a deficiency perhaps caused by genetics or an immune response triggered by a virus.
Type 2 diabetes is a different disease, where the body has difficulty using insulin. It often begins later in life, and can lead to loss of insulin production. Type 2 diabetes can be triggered by genetics and lifestyle, such as being overweight and having a poor diet.
Insulin is a hormone that unlocks cells, letting glucose in, where it is either used as energy or stored as fuel. Without insulin, glucose remains in the blood and is passed through the kidneys into the urine. Diabetics produce a lot of urine as the glucose draws water out of the body, leading to thirst. Weight loss and a lack of energy result when glucose cannot get into the body’s cells.
The Discovery of Insulin
Canadian Dr Frederick Banting, together with medical student Charles Best, building on the work of earlier physicians, isolated insulin from the pancreases of dogs and cows in 1921.
In 1922, the insulin was first tested on 14-year-old Leonard Thompson, a diabetic, and it restored him to health.
No other drug in the history of medicine changed the lives of so many people so suddenly. Banting was jointly awarded the Nobel Prize in 1923 for his work in diabetes.
The many types of insulin can be divided into those that act quickly and for a short time (taken just before a meal), and those that act slowly and for a long time (taken once or twice a day to keep glucose levels stable). Many diabetics are prescribed both forms of insulin.
While life-saving, injected insulin is unable to match the body’s own insulin for blood-glucose control. When blood-glucose levels fall too low, it can lead to confusion and even coma, and sugar needs to be given by mouth or injection. Chronically raised blood-glucose levels can damage the eyes, kidneys, nerves and heart.
Pumps that constantly monitor blood glucose and adjust the amount of insulin injected are available, and may better control blood-glucose levels. Pancreas transplants are also occasionally available. An insulin pill to replace needles has proved difficult for researchers, as insulin is destroyed in the stomach. For now, insulin injections are indispensable for the health of diabetics across the world.