S tier · elite
Tirzepatide holds three approved indications, the largest weight-loss effect of any approved agent in a head-to-head trial (SURMOUNT-5), and now has both a dedicated heart failure outcome trial (SUMMIT) and a completed 13,000-patient cardiovascular outcomes trial (SURPASS-CVOT).
tirzepatide
Tirzepatide is a 39-amino-acid dual GIP and GLP-1 receptor agonist approved for type 2 diabetes, chronic weight management and obstructive sleep apnoea. It has produced the largest mean weight reductions of any approved incretin in randomised trials and demonstrated cardiovascular non-inferiority to dulaglutide, though superiority on MACE was not established.
the explanation
Tirzepatide acts on two gut hormone receptors instead of one, and in trials it produced more weight loss than semaglutide when the two were compared directly. It also reduced heart failure events in people with obesity-related heart failure, but stomach side effects are common and it has not yet been shown to beat other drugs at preventing heart attacks.
regulatory status
FDA-approved 2022 (Mounjaro); 2023 (Zepbound)
Approved for type 2 diabetes (May 2022), chronic weight management (November 2023) and moderate-to-severe obstructive sleep apnoea in adults with obesity (December 2024).
how it works · proposed mechanism
Tirzepatide engages two distinct incretin receptors with deliberately unequal potency.
Dual incretin receptor activation
Tirzepatide binds both GIP and GLP-1 receptors, with higher relative potency at GIPR. This dual engagement produces greater glycaemic and weight effects than GLP-1 agonism alone in head-to-head trials.
GIP contribution to appetite
GIP receptor agonism in hypothalamic circuits appears to add to the anorexigenic signal while, in preclinical models, dampening GLP-1-induced nausea pathways in the area postrema. The precise human contribution of GIPR agonism versus antagonism remains actively contested.
Adipose tissue handling
GIP receptors are expressed on adipocytes, where signalling influences lipid buffering and blood flow. Whether this translates to a distinct human body-composition advantage over GLP-1 monotherapy is not resolved.
Cardiac and haemodynamic effects
In SUMMIT, tirzepatide reduced the composite of cardiovascular death or worsening heart failure alongside falls in hsCRP and improvements in exercise capacity. A CMR substudy reported reductions in left ventricular mass and paracardiac adipose tissue.
what’s reported
evidence shape
6 sourcesThe composition of the cited literature by study type. This describes the shape of the evidence, not its quality — and it does not by itself set the grade.
⚠ the catch
SURPASS-CVOT failed its superiority test against dulaglutide (HR 0.92, p=0.09 for superiority), so despite far larger weight and HbA1c effects, tirzepatide has not been shown to prevent more atherosclerotic events than an older, cheaper GLP-1 agonist. Gastrointestinal adverse events were also more frequent than with dulaglutide.
key published findings
- SURMOUNT-1 (n=2,539, 72 weeks) reported mean weight reduction of 16.0%, 21.4% and 22.5% at 5 mg, 10 mg and 15 mg respectively versus 2.4% with placebo in adults with obesity or overweight without diabetes.
- SURPASS-CVOT (n=13,165, median 4-year follow-up) reported three-point MACE in 12% on tirzepatide versus 13% on dulaglutide (HR 0.92), meeting non-inferiority (p=0.003) but not superiority (p=0.09).
- SUMMIT (n=731, median ~2 years) reported cardiovascular death or worsening heart failure in 36 tirzepatide versus 56 placebo participants (HR 0.62, 95% CI 0.41–0.95, p=0.026) in obesity-related HFpEF, with 11.6% greater weight loss.
- SURMOUNT-5 (n=751, 72 weeks) reported −20.2% weight change with tirzepatide 10–15 mg versus −13.7% with semaglutide 1.7–2.4 mg (p<0.001), a mean 22.8 kg versus 15.0 kg loss.
- SURPASS-2 (n=1,879, 40 weeks) reported HbA1c reductions of 2.01%, 2.24% and 2.30% for tirzepatide 5/10/15 mg versus 1.86% for semaglutide 1 mg, with 11.2 kg versus 5.7 kg weight loss at the top dose.
limitations of the evidence
- SURPASS-CVOT used an active comparator rather than placebo, so the absolute cardiovascular benefit of tirzepatide versus no incretin therapy has not been directly quantified.
- The mechanistic role of GIP receptor agonism in humans is unsettled, with credible preclinical arguments that GIPR antagonism could produce similar effects.
- SUMMIT was a modestly sized event-driven trial (92 primary events total), so the HFpEF benefit estimate has wide confidence intervals and has not been independently replicated.
identity
| full name | Tirzepatide (LY3298176, dual GIP/GLP-1 receptor agonist) |
| category | Metabolic |
| modality | peptide |
| formula | C225H348N48O68 |
| molar mass | 4813.53 g/mol |
| cas | 2023788-19-2 |
| half-life | ~5 days |
| sequence | Y-Aib-EGTFTSDYSIΨLDKIAQ-K(γGlu-AEEA-AEEA-C20 diacid)-AFVQWLIAGGPSSGAPPPS-NH2 (39 residues; Aib at positions 2 and 13) |
laboratory handling
| storage | Lyophilised reference material is typically stored at −20 °C in sealed, desiccated vials protected from light; reconstituted solutions are generally kept at 2–8 °C for short-term work or aliquoted and frozen at −80 °C to avoid repeated freeze-thaw cycles. |
| solubility | Sparingly soluble in neutral water; laboratory stocks are commonly prepared in bacteriostatic or sterile water, or in DMSO for in vitro assay use. |
| co-studied with | Tirzepatide is the active comparator against which most next-generation obesity agents including CagriSema and retatrutide are now benchmarked. |
Handling information describes laboratory practice for a research reagent. It is not a preparation guide for use in humans.
the receipts
6 citedNEJM · 2022 · official
American College of Cardiology · 2026 · official
American College of Cardiology · 2024 · peer-reviewed
NEJM · 2025 · peer-reviewed
NEJM · 2021 · peer-reviewed
others in Metabolic