Insulin: The Holy Grail of Medicine

The most dramatic story in Canadian medicine had an inauspicious beginning.

A shy part-time instructor at the University of Western’s medical school, Frederick Banting, came to visit the august professor of physiology J.J.R. Macleod in his office at the University of Toronto. A skeptical Macleod listened to the shy and hesitant Banting describe how an idea had come to him, one sleepless night, of how isolating a secretion in the pancreas might hold the key to curing diabetes. This substance was nothing less than the holy grail of medicine and Macleod demanded to know why Banting thought he could succeed while so many had failed.

Diabetes is a debilitating illness caused by the body’s inability to metabolize food. Other researchers knew that the disease was related to the pancreas, but had no idea how. The prognosis for those who developed the disease early was dismal. They suffered intense hunger and thirst and faced coma and death. The only, highly questionable, treatment was starvation.

Banting, a farmer’s son from Alliston, Ont, persisted and to his credit Macleod relented and provided the young man with a laboratory, some experimental dogs and an assistant, Charles Best.

Banting was not the first researcher to suspect that certain cells in the pancreas, called the islets of Langerhans, release a substance into the blood which holds the key to diabetes. Many had tried to find the substance, and failed. Banting got his idea for finding this elusive substance when he learned that although a dog gets diabetes if you remove its pancreas, it does not get diabetes if you just tie off the pancreas.

Banting and Best began their experiments in July of 1921. They operated on the dogs, tying off the ducts through which digestive juices leave the pancreas. Several weeks later, Banting removed the withered organs and then injected an extract from the islet tissues into dogs whose pancreas he had removed. The principal symptom of diabetes is a high level of sugar in the blood. To Banting’s delight, his injections lowered the level of sugar in the blood of several diabetic dogs.

Charles Best (left) and Frederick Banting (right), with a dog used in their experiments to isolate insulin (Thomas Fisher Rare Book Library, U of T).

The route to scientific discovery is rarely direct. Banting’s operations on the unfortunate dogs were unnecessary. He soon realized that the substance can be extracted from a whole pancreas and the team found a less controversial source in cattle. But his experiments did show that there was a diabetes-fighting substance in the pancreas. And they encouraged Professor Macleod and biochemist James Collip to try to do what Banting and Best lacked the scientific skill to do — to isolate and purify the mysterious substance.

On January 23, 1922, a 14-year old boy who was dying of diabetes in Toronto General Hospital was injected with an extract that Collip had made and purified from ox pancreas. The dramatic improvement in the boy’s condition was convincing proof that the Toronto team had made a life-saving discovery.

While news began to spread about the breakthrough, the team suffered a huge setback. Incredibly, they lost the ability to retrace the delicate, complex procedure of making insulin (as Macleod had named it). When they finally did regain the knack, the effect of their discovery was sensational. A doctor in Boston likened the appearance of insulin to a religious miracle, as patients were brought back almost literally from the dead. A conference in Washington hailed the discovery as “one of the greatest achievements of modern medicine.”

After the achievement came the bickering over who should get the glory. Banting was incensed when the Nobel committee ignored Best and made him share the prize with Macleod, whom he had never liked. Critics of Banting pointed out that his original idea was wrong and that his experiments were shoddy, but since the discovery would never have been made without him, his fame was assured. While Banting shared his prize money with Best, Macleod shared his with Collip.

The men had little to do with one another afterwards. Macleod returned to Scotland. Collip went on to be the first to isolate the parathyroid hormone. Best replaced Macleod as professor at University of Toronto. Banting, who died in an air crash in 1941, tried to bury the hatchet and perhaps gave the best epitaph: “I have always thought that Science was greater than the individual and that Insulin therefore spoke for itself and the story needed no further telling.”

Although not a “cure” for diabetes, insulin has saved the lives of millions. Even with insulin, diabetes patients develop health problems — such as blindness and kidney disease — more frequently than healthy people, and diabetes remains a major cause of death. But thanks to the discovery of insulin, millions of people who suffer from diabetes now lead relatively long and normal lives.

James H. Marsh is editor in chief of The Canadian Encyclopedia. 

First published in the National Post and CanWest newspaper chain, now featured on The Canadian Encyclopedia.

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