A Science Odyssey
People and Discoveries

Banting and Best isolate insulin

Photo: In this lab, Banting and Best carried out early experiments which led to the discovery of insulin.

In 1920, Canadian surgeon Frederick Banting visited the University of Toronto to speak to the newly appointed head of the department of physiology, John J.R. Macleod. Macleod had studied glucose metabolism and diabetes, and Banting had a new idea on how to find not only the cause but a treatment for the so-called "sugar disease."

Late in the nineteenth century, scientists had realized there was a connection between the pancreas and diabetes. The connection was further narrowed down to the islets of Langerhans, a part of the pancreas. From 1910 to 1920, Oscar Minkowski and others tried unsuccessfully to find and extract the active ingredient from the islets of Langerhans. While reading a paper on the subject in 1920, Banting had an inspiration. He realized that the pancreas' digestive juice was destroying the islets of Langerhans hormone before it could be isolated. If he could stop the pancreas from working, but keep the islets of Langerhans going, he should be able to find the stuff! He presented this idea to Macleod, who at first scoffed at it. Banting badgered him until finally Macleod gave him lab space, 10 experimental dogs, and a medical student assistant.

In May, 1921, as Macleod took off for a holiday in his native Scotland, Banting and his assistant Charles Best began their experiments. By August they had the first conclusive results: when they gave the material extracted from the islets of Langerhans (called "insulin," from the Latin for "island") to diabetic dogs, their abnormally high blood sugars were lowered. Macleod, back from holiday, was still skeptical of the results and asked them to repeat the experiment several more times. They did, finding the results the same, but with problems due to the varying purity of their insulin extract.

Macleod assigned chemist James Bertram Collip to the group to help with the purification. Within six weeks, he felt confident enough of the insulin he had isolated to try it on a human for the first time: a 14-year-old boy dying of diabetes. The injection indeed lowered his blood sugar and cleared his urine of sugars and other signs of the disease. Banting and Best published the first paper on their discovery a month later, in February, 1922. In 1923, the Nobel Prize was awarded to Banting and Macleod for the discovery, and each shared their portion of the prize money with the other researchers on the project.

Ironically, Banting's original idea wasn't entirely correct. He and Best later found they could obtain insulin even from an intact pancreas. Improved technology for testing and detecting sugar in the blood and urine provided information that earlier researchers didn't have, and this encouraged them to pursue a line of thinking that may have looked like a dead end to those working in the decades before them.

The discovery of insulin was one of the most revolutionary moments in medicine. Though it took some time to work out proper dosages and to develop manufacturing processes to make enough insulin of consistent strength and purity, the introduction of insulin seemed literally like a miracle. One year the disease was an automatic death sentence; the next, people -- even children -- had hopes of living full and productive lives even with the disease. Estimates show there are more than 15 million diabetics living today who would have died at an early age without insulin.

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