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Macleod, J.J.R. (John)

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J.J.R. (John) Macleod
(September 6, 1876 - March 16, 1935)
Born in Scotland
Year of Discovery: 1922


Scientist Who Named Insulin

John Macleod was a world-renowned expert on carbohydrate metabolism. He conducted a vibrant laboratory at the University of Toronto and had a keen interest in diabetes, a subject about which he'd written a book. So, it was not surprising he greeted the young Frederick Banting, a struggling physician, with skepticism. Banting had a theory about diabetes, based upon a single research paper he'd read, but no hands-on research experience.

Diabetes is a disease that restricts the body's ability to produce or use insulin. Insulin is produced in the pancreas of healthy individuals and is critical to the regulation of blood sugar levels. The body runs on sugar - specifically a sugar known as glucose. Glucose is the body's primary energy source, but without insulin the body can't convert sugars, starches, and other foods into energy. Instead, the sugars build up in the system and spill into the blood. This is why diabetics must constantly test their blood to determine the amount of glucose it contains, and to determine the amount of insulin they need to effectively utilize the glucose. Type 1 diabetes indicates the inability of the body to produce insulin, while type 2 diabetes indicates the body's inability to effectively use the insulin it produces (also known as insulin resistance).  Both types can have side effects of heart disease, circulatory problems, kidney failure, blindness, and foot ulcers. Prior to Banting's discovery there were few options available to treat diabetes. Diet modification was prevalent and reasonably effective for many type-2 diabetics. But type-1 diabetes was a tragic disease. Also known as childhood diabetes, the body's complete lack of insulin leads inevitably to death. Before Banting, the only method of delaying death was a starvation diet, typically consisting of fewer than 500 calories per day. This might extend the life of tiny, emaciated children for a year. Today, diabetes continues to be a major problem. Over 170 million people suffer from diabetes worldwide, and five percent of all global deaths annually are a result of diabetes.

Macleod reluctantly assigned Charles Best, a young graduate student, to assist Frederick Banting with his research. This was in the spring of 1921 and, after the arrangements had been made, Macleod journeyed to his native Scotland for the summer. Upon his return to the laboratory, Macleod was met by an enthusiastic Banting, claiming a breakthrough that proved his theory.  Still skeptical after reviewing Banting's notes, Macleod insisted the experiments be repeated, ensuring the results were meticulously recorded, leaving absolutely no room for error. Macleod's dedication to precise scientific method yielded the proof the team needed to present their discovery - insulin - to the wider scientific community. Macleod put in place all the rigorous experiments needed to confirm and improve the drug so that it could be used on humans. He brought in James Collip, a skilled biochemist, to help refine and purify the raw extract developed by Banting and Best. The efforts paid off and, in early 1922, the first human trials were completed. Parents with diabetic children rushed to Toronto, creating a shortage of insulin. The University quickly partnered with the American pharmaceutical company, Lilly. There the purified form of insulin was mass-produced and became readily available to diabetics worldwide, saving millions of lives. He also changed Banting and Best‘s name for their isolated substance from isleton to its more familiar name today, insulin.

Introduction by Tim Anderson


Table of Contents

Links to More Information About the Scientist
Key Insight
Key Experiment or Research
Key Contributors
Quotes by the Scientist
Quotes About the Scientist
Fun Trivia About The Science
The Science Behind the Discovery
Personal Information
Science Discovery Timeline
Recommended Books About the Science
Books by the Scientist
Books About the Scientist
Major Academic Papers
Curriculum Vitae
Links to Science and Related Information on the Subject


Links to More About the Scientist & the Science biography: biography:

Google timeline of Macleod's research:

Macleod's Papers & News Clips
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Key Insight

Key Experiments or Research


Key Contributors

The Team
Explore other scientists who furthered this lifesaving advance.

Lifesavers: Insulin

Frederick Banting
Discovered the first true miracle drug: insulin.
James "Bert" Collip
Developed insulin into a useable human drug.
Charles Best
Joined Banting's insulin research team based on the flip of a coin.

Quotes by the Scientist

Quotes About the Scientist


Fun Trivia About the Science

The Science Behind the Discovery

Personal Information

Scientific Discovery Timeline

Recommended Books About the Science

Books by the Scientist

Books About the Scientist



Major Academic Papers Written by the Scientist

Curriculum Vitae

Links to Information on the Science