Tirzepatide: Dual GIP and GLP-1 Receptor Agonism in Metabolic Research
Tirzepatide is a synthetic peptide that activates two metabolic signaling pathways: the glucose-dependent insulinotropic polypeptide, or GIP, receptor and the glucagon-like peptide-1, or GLP-1, receptor. These receptors are involved in glucose-dependent insulin secretion, appetite regulation, gastric emptying, and energy balance.
One of the largest studies of tirzepatide in adults with obesity was the phase 3 SURMOUNT-1 trial. The study enrolled 2,539 adults with obesity or overweight and at least one weight-related complication, excluding diabetes. After 72 weeks, the average body-weight changes were approximately −15.0% with the 5-mg group, −19.5% with the 10-mg group, and −20.9% with the 15-mg group, compared with −3.1% with placebo. The most commonly reported adverse events were gastrointestinal and occurred mainly during dose escalation.
FDA-approved tirzepatide formulations are prescription drugs with specific indications, manufacturing requirements, warnings, and quality controls. Current labeling includes a boxed warning concerning thyroid C-cell tumors observed in rats, although the relevance of this finding to humans is unknown. Published results involving an approved formulation should not be interpreted as evidence that an independently manufactured research material is clinically interchangeable with that formulation.
Research significance
Tirzepatide research demonstrates how simultaneous activation of two incretin receptors may produce metabolic effects that differ from single-receptor GLP-1 agonism. Ongoing research continues to examine cardiovascular outcomes, body composition, sleep apnea, diabetes, obesity-related complications, and long-term weight maintenance.
References
- Jastreboff AM, Aronne LJ, Ahmad NN, et al. Tirzepatide once weekly for the treatment of obesity. New England Journal of Medicine. 2022;387:205–216. DOI: 10.1056/NEJMoa2206038.
- U.S. National Library of Medicine. Zepbound — tirzepatide injection, prescribing information. DailyMed. Revised 2026.
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References to clinical trials or FDA-approved prescription products describe the specific materials and formulations evaluated in those studies. These results do not establish that an independently manufactured research material has the same identity, purity, potency, pharmacokinetics, safety, or effectiveness.
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