History of Insulin: Discovery to Treatment

Insulin research achieved its breakthrough in 1921, and insulin was first administered to a person with diabetes in 1922. The history of insulin is a story of teamwork—not one researcher’s achievement.

Diabetes Care Before Insulin

Before insulin, people with what we now call type 1 diabetes usually died soon after diagnosis. Severe food restriction sometimes prolonged survival, but couldn't replace the missing hormone. Understanding what insulin does explains why its arrival changed so much.

The Toronto Breakthrough in 1921

Banting, Best, Macleod and Collip

At the University of Toronto, Frederick Banting and Charles Best tested pancreatic extracts in dogs. John Macleod provided laboratory resources, expertise and scientific direction. James Collip subsequently improved purification, making the extracts more suitable for clinical use. Their work built on earlier pancreatic research.

Leonard Thompson’s Treatment in 1922

Why Purification Mattered

Fourteen-year-old Leonard Thompson received his first injection on January 11, 1922. The crude extract produced limited benefit and an adverse reaction. On January 23, treatment with Collip’s more purified preparation markedly reduced his blood glucose. That distinction matters: the first injection wasn't the successful treatment that followed.

The 1923 Nobel Prize

The Nobel Prize account names Banting and Macleod as the 1923 medicine laureates “for the discovery of insulin.” Banting shared his prize money with Best; Macleod shared his with Collip.

Production and Delivery Evolve

Early insulin came from animal pancreases, principally cattle and pigs. Commercial production expanded in 1923. Longer-acting types of insulin followed in subsequent decades.

Recombinant human insulin, first approved in the US in 1982, uses engineered microorganisms to produce insulin matching the human hormone. Insulin analogues later altered its action profile. Meanwhile, insulin delivery methods expanded from syringes to pens, pumps and automated delivery systems.

Frequently Asked Questions

How long has insulin been used? Since January 1922—more than 104 years as of October 2026.

Was the first insulin human insulin? No. It was animal-derived, decades before recombinant production.

Does everyone with diabetes need insulin? No. Insulin helps glucose enter cells. Among the key type 1 and type 2 diabetes differences, people with type 1 need insulin to survive; some people with type 2 need it, while others use different treatments. NIDDK’s diabetes treatment overview explains these roles.