Who invented tirzepatide? A team at Eli Lilly, building on an idea that came out of academic labs. The U.S. patent on the molecule names four Lilly scientists: Jorge Alsina-Fernandez, Tamer Coskun, Bengt Krister Bokvist and Robert Chadwick Cummins. Lilly's 2018 discovery paper credits Alsina-Fernandez with designing it. The idea underneath, one molecule that flips the switches for two gut hormones at once, was pioneered by Richard DiMarchi at Indiana University and Matthias Tschöp in Munich.
So there's no lone inventor. There's a relay, and it starts with a hormone most of the field had given up on.
How GLP-1 itself was found is in who discovered GLP-1; what the drug does in the body is in how tirzepatide works. This page is about the people.
The problem: a gut hormone the field had written off
GIP (glucose-dependent insulinotropic polypeptide) is a hormone the gut releases after a meal. Like GLP-1, it tells the pancreas to release more insulin when blood sugar is up. It was found first: its full sequence was published in 1971 (Brown and Dryburgh, Can J Biochem 1971), and by 1973 it had been shown to raise insulin in people (Dupré et al., J Clin Endocrinol Metab 1973).
Then came the setback. In 1993, Michael Nauck's team in Göttingen tested both hormones in nine people with type 2 diabetes and nine matched volunteers. GIP's peak insulin effect was 54% lower with diabetes, while GLP-1 kept most of its punch (Nauck et al., J Clin Invest 1993). Drug makers followed the evidence to GLP-1.
A small Danish study reopened the door. Eight people with poorly controlled type 2 diabetes had their blood sugar brought close to normal with insulin for four weeks. Afterward, their late insulin response to GIP was about three times bigger (Højberg et al., Diabetologia 2009). GIP wasn't useless. High blood sugar seemed to be muffling it.
Dual GIP GLP-1 agonist history: DiMarchi and Tschöp
Richard DiMarchi is a peptide chemist. His Indiana University profile calls him a former group vice president at Eli Lilly and later Novo Nordisk, known for work on the insulin Humalog (Indiana University). After joining Indiana University in 2003, he began a long collaboration with Matthias Tschöp, a German physician and scientist who suspected one hormone wouldn't be enough to treat obesity (AAAS).
They first built a single molecule that hit the GLP-1 and glucagon receptors, then turned to GIP. In the AAAS account, Danish work showing GIP could work again once blood sugar had improved for a few weeks changed their thinking. "We envisioned GLP-1 as the first stage of the rocket to improve glycemic control, and then GIP would be able to function," DiMarchi said.
Their 2013 paper described one peptide, stitched together from pieces of both hormones, that activated both receptors about equally. The authors reported better blood-sugar control than GLP-1-only drugs in rodents, monkeys and people, and more fat loss in obese rodents, while a GIP-only drug barely moved weight (Finan et al., Sci Transl Med 2013). Brian Finan was first author and Tschöp senior author, with DiMarchi among 33 names.
Who invented tirzepatide at Eli Lilly
Lilly built its own molecule, and it differs from the 2013 design. Tirzepatide is based on GIP's sequence, with two unusual amino acids and a 20-carbon fatty acid that lets it ride on albumin, the main protein in blood. The Mounjaro label (revised August 2026) gives it a half-life, the time the body takes to clear half a dose, of about five days (DailyMed).
The patent, U.S. 9,474,780, "GIP and GLP-1 co-agonist compounds," traces to a first filing on January 9, 2015, and was granted on October 25, 2016. It names the four inventors above and is assigned to Eli Lilly (Google Patents).
The 2018 discovery paper, under the code name LY3298176, has 16 authors from Lilly and Duke University. Its contributions note is unusually plain: "J.A-F. was responsible for molecule design," while Coskun, the first author, ran the obese-mouse studies (Coskun et al., Mol Metab 2018). The paper cites the 2013 study among earlier dual agonists, and AAAS writes that DiMarchi's approach "inspired the development of the drug tirzepatide."
Twincretin history: from LY3298176 to Mounjaro
The first human study began in May 2016 (ClinicalTrials.gov). Phase 2 followed: 318 adults with type 2 diabetes, 26 weeks, four doses against placebo and dulaglutide, an older weekly GLP-1 drug. HbA1c, a three-month average of blood sugar, fell by up to 1.94 points, against 0.06 on placebo and 1.21 on dulaglutide. Stomach side effects rose with dose, from 23.1% at 1 mg to 66.0% at 15 mg (Frías et al., Lancet 2018).
The Lancet ran a comment beside it by Michael Stumvoll and Tschöp titled "Twice the benefits with twincretins?" (Lancet 2018). The nickname stuck.
| Date | Milestone |
|---|---|
| October 2013 | The academic dual-incretin paper |
| January 9, 2015 | Lilly's tirzepatide patent first filed |
| May 13, 2022 | Mounjaro, for type 2 diabetes |
| November 8, 2023 | Zepbound, for chronic weight management |
| August 27, 2026 | Mounjaro adds cardiovascular risk reduction |
The first two drug dates come from the FDA's signed Mounjaro letter and its Zepbound announcement. The trials in between are summarized in tirzepatide clinical trials.
Prizes for the people behind tirzepatide
- 2024: the Intellectual Property Owners Education Foundation named the four Lilly inventors its Inventors of the Year, jointly with the Novo Nordisk team behind semaglutide (IPOEF).
- April 4, 2024: AAAS gave DiMarchi and Novo Nordisk's Lotte Bjerre Knudsen its Mani L. Bhaumik Breakthrough of the Year Award, saying he "transformed thinking about the hormones this class of therapies should mimic."
- July 14, 2026: the Broermann Medical Innovation Award named Tschöp, now president of LMU Munich, DiMarchi and Svetlana Mojsov of Rockefeller University as its 2026 laureates. The €1 million prize is presented on November 17, 2026 (Broermann Award; LMU).
As of September 23, 2026, the day this article was written, Indiana University's Gill Institute is holding its 2026 incretin symposium, with a keynote by DiMarchi (Indiana University). Two of its four awards go to 2013 co-authors: Timo Müller of LMU Munich and Brian Finan, now at Eli Lilly (Gill Institute).
Where the tirzepatide discovery stands today
The drug is still picking up uses. On August 27, 2026, the FDA signed a letter adding one to Mounjaro: lowering the risk of heart attack, stroke and cardiovascular death in adults with type 2 diabetes at high risk. It rests on SURPASS-CVOT, a trial of tirzepatide against dulaglutide.
As of September 23, 2026, the day this article was written, the FDA's Orange Book, its list of approved drugs and their patents, shows the four inventors' patent on Mounjaro expiring May 13, 2036 (FDA Orange Book).
What the discovery did not settle
Credit, for one. The patent names four people, the discovery paper sixteen, the prizes a different set again. None of those lists is wrong; they answer different questions.
The biology isn't settled either. Lab work led by Lilly scientists finds tirzepatide leans toward the GIP receptor rather than hitting both evenly (Willard et al., JCI Insight 2020). And researchers still debate whether that receptor should be switched on or blocked. In mice, both approaches added to GLP-1's weight loss, through different routes (Gutgesell et al., Nat Metab 2025). Amgen's maridebart cafraglutide, which blocks the GIP receptor while activating GLP-1's, produced 12.3% to 16.2% mean weight loss at 52 weeks in a phase 2 trial in people with obesity (Jastreboff et al., NEJM 2025).
The history also says nothing about one person's response or what is in a particular vial. Through Promise, tirzepatide is dispensed as a compounded medication, which is different from an FDA-approved product: the formulation offered here is not FDA-approved. A licensed provider may still prescribe a compounded formulation; that decision is between you and your doctor. At Promise, a licensed provider reviews every request, and not everyone qualifies.
