The discovery of insulin in Toronto: beginning a 100 year journey of research and clinical achievement


There has been a great deal of controversy regarding priority of discovery of insulin. Indeed, many scientists made important and, in some cases, seminal contributions to identifying the endocrine role of the pancreas and the potential for pancreatic extracts to have a glucose-lowering effect. The purpose of this article is to describe the early experiences with respect to research leading to the discovery of insulin in Toronto (ON, Canada). The experiments conducted at the University of Toronto resulted in the first demonstration that a pancreatic extract could be prepared that would consistently lower glucose, reverse ketosis and arrest the catabolic effects of type 1 diabetes. The remarkably rapid commercial production of insulin soon followed. The Toronto story begins on 17 May 1921, when Frederick Banting and Charles Best began their summer research project in the laboratory of John James Rickard Macleod, and we are now celebrating the 100th anniversary of this landmark achievement. The article herein outlines the steps leading up to the discovery of insulin and provides an overview of some of the key developments in insulin therapy over the past 100 years.

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Authors’ relationships and activities

BZ reports serving on scientific advisory boards for Eli Lilly, Novo Nordisk and Sanofi. MF declares that there are no relationships or activities that might bias, or be perceived to bias, their work.

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MF wrote the initial draft of the article. Both authors were responsible for revising it critically for important intellectual content and approved the version to be published.

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Correspondence to Michael Fralick.

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Fralick, M., Zinman, B. The discovery of insulin in Toronto: beginning a 100 year journey of research and clinical achievement. Diabetologia (2021).

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  • Banting
  • Best
  • Diabetes
  • Insulin
  • Review
  • Type 1 diabetes