Nobel Prize for Insulin: What Happened in 1923

Frederick Banting and John Macleod won the Nobel prize for insulin in 1923. Charles Best and James Collip were central to the Toronto work, but weren't named as laureates, the official prize recipients. Both later shared in the prize money.

A telegram dated October 25, 1923 anchors the anniversary. It recognized a treatment already being used in people. The discovery and the announcement happened in different years.

The Nobel prize for insulin: the October 25 telegram

The University of Toronto's Thomas Fisher Rare Book Library holds a document titled “Telegram to Doctor Frederick G. Banting 25/10/1923”. Its catalogue says the telegram informed Banting that he and Macleod had won the year's Nobel Prize.

The Nobel Foundation's 1923 record names Frederick Grant Banting and John James Rickard Macleod. Its reason is just five words: “for the discovery of insulin.” Each received half the award.

The telegram supplies the October date. The Nobel page supplies the official recipients and wording. Together, they show which date the anniversary marks and what the prize recognized.

The day before: insulin treatment had already begun

On October 24, 1923, patients were already receiving insulin. The award recognized earlier work; it didn't introduce a medicine that morning.

Before insulin treatment, severe diabetes often meant death, particularly for children whose bodies made too little insulin. Insulin is a hormone, a chemical messenger that helps regulate blood sugar. Doctors used severely restricted diets to buy time. FDA's history of insulin describes the limits of that approach.

Banting and Best began experiments at the University of Toronto in May 1921. Macleod provided the laboratory and scientific direction. Collip, a visiting scientist from the University of Alberta, worked on removing unwanted material from extracts of the pancreas, the organ that makes insulin.

At Toronto General Hospital, 14-year-old Leonard Thompson received an extract on January 11, 1922. The original March 1922 report in the Canadian Medical Association Journal describes limited benefit from that first preparation. Treatment with a more concentrated preparation began January 23, followed by lower blood sugar and other reported improvements.

The important step was making the extract usable in patients. Finding an insulin-related effect in an animal was only part of the work.

Modern tirzepatide brings the story back to the pancreas. It helps the body release insulin through gut hormone signals. It doesn't supply insulin.

What the award changed—and who shared it

The prize put two names on an international honor. It didn't turn a four-person effort into a two-person discovery.

A second Toronto document, “Telegram to Dr. F. G. Banting 27/10/1923”, records a message from physician Elliott Joslin. Its catalogue refers to Banting's request the previous day to announce that he would share the prize with Best.

A 2023 archival review in Acta Diabetologica reports the financial split: Banting shared half his portion with Best; Macleod shared half his with Collip. Best and Collip became recipients of shared funds, rather than additional Nobel laureates.

That distinction explains much of the “Banting and Best” confusion. Best belongs in the discovery story. Macleod belongs on the formal prize record.

From animal extracts to defined molecules: 1923–1984

1923: wider production. Toronto's partnership with Eli Lilly helped expand manufacturing. FDA's history records general distribution by Lilly in fall 1923. Producing reliable supplies became part of the clinical advance.

1955 and 1958: reading the chain. Frederick Sanger established insulin's sequence, the order of its amino acids, in 1955. A peptide is a chain of amino acids, the building blocks of proteins. The Nobel Foundation's chemistry history dates that work. His 1958 chemistry prize recognized protein structure, especially insulin.

1960 and 1977: measuring insulin. Rosalyn Yalow and Solomon Berson's 1960 Journal of Clinical Investigation paper described measuring the body's own insulin in blood. Their method, radioimmunoassay, measured tiny amounts using antibodies, proteins that bind particular targets. A radioactive tag made the amount detectable. Our 1977 Nobel hormone history follows that separate advance.

1979 and 1982: making human insulin in bacteria. A 1979 paper by Goeddel and colleagues in PNAS described using genes made in the laboratory to produce insulin chains in bacteria. Genes carry biological instructions. This was recombinant technology: putting genetic instructions into another organism to make a substance. FDA's history gives October 28, 1982 as the date it authorized Humulin, the first human insulin product made with genetically programmed bacteria.

1984: another manufacturing route. Bruce Merrifield's separate chemistry prize recognized building molecules on solid beads. The 1984 peptide-synthesis history explains that method. Insulin's story had opened several different paths into hormone medicine.

That manufacturing story continues in semaglutide. The Ozempic label says its main peptide chain is made through yeast fermentation, meaning yeast is grown to produce it. Chemical changes then help the molecule last longer.

From insulin to GLP-1 medicines

Insulin is a peptide hormone containing 51 amino acids in two linked chains. GLP-1, a gut hormone released after eating, sends the pancreas a different message.

The 1986–1987 laboratory experiments behind the discovery of GLP-1 established its active forms and insulin-releasing action. They came decades after the insulin Nobel. Incretins are gut hormones that help the pancreas release insulin after food arrives.

Semaglutide activates the GLP-1 receptor, a cell's receiving switch. Tirzepatide activates that switch and the receptor for GIP, another incretin hormone.

The Ozempic label's section 12.1 describes semaglutide's insulin release as “glucose-dependent”: the response depends on the blood sugar level. High blood sugar needn't be actively rising for that response to occur. These medicines act through hormone signals; they don't supply insulin.

What changed recently, and what matters now

As of October 1, 2026, the day this article was written, an FDA decision signed August 27, 2026 has added a use for Mounjaro. It covers adults at high risk with type 2 diabetes, where the body has trouble using insulin. The use is reducing major heart and blood vessel events: heart attack, stroke and death from heart or blood vessel causes. The accompanying Mounjaro label states “Revised: 08/2026.”

The insulin connection also matters for medication combinations. Mounjaro's section 5.3 and the Ozempic label, marked “Revised: 05/2026,” warn of “an increased risk of hypoglycemia, including severe hypoglycemia.” Hypoglycemia means low blood sugar. That warning concerns use alongside insulin or a sulfonylurea, a medicine that prompts insulin release.

Glucose-dependent action doesn't make that combination risk disappear. A clinician considers the existing medicines, blood sugar measurements and any needed dose changes.

What a prescribed route adds today

The Nobel recognized a discovery. The modern label describes a particular branded product. Neither settles whether a different preparation fits one person's medical history.

Through Promise, tirzepatide and semaglutide are dispensed as compounded medications, meaning a pharmacy prepares them for specific prescriptions. They are different from FDA-approved products: the formulations offered here are not FDA-approved. The new Mounjaro indication does not transfer to those preparations.

A licensed provider may still prescribe — that decision is between you and your doctor.

At Promise, a licensed provider reviews every request, and not everyone qualifies. When prescribed, a licensed U.S. compounding pharmacy prepares the medication, with follow-up through the clinical relationship.

That is where this history meets an ordinary visit: the exact ingredient, the medicines already being used and the reason for treatment all matter.