Trulicity vs Zepbound: Two Eli Lilly GLP-1 Molecules

Last reviewed: May 12, 2026 Last updated: May 12, 2026

Written by: Jay Hastings , CEO of PlexusDx

Jay Hastings is the CEO of PlexusDx, a precision health company focused on genetic testing, blood biomarker insights, and personalized wellness recommendations. He has more than 20 years of experience across healthcare innovation, genomics, laboratory operations, healthcare investing, and strategic finance. His work has included scaling healthcare startups, leading CLIA lab integrations, and helping expand consumer access to precision health tools.

Medically reviewed by: Jayden Lee, PharmD, EMBA

Jayden Lee, PharmD, EMBA, is the PlexusDx Medical Science Liaison with a PharmD and MBA specializing in pharmacogenomics and clinical product development, with a proven ability to bridge the gap between genomic research and practical patient outcomes. Dr. Lee has more than 10 years of professional experience in clinical pharmacy, academia, and research.

This piece comes from the PlexusDx Education Hub, where we compare GLP-1 therapies molecule by molecule and connect them to the genetic pathways that shape metabolic response. Browse all Peptides & GLP-1 education

This is an independent editorial comparison. PlexusDx has no commercial relationship with the manufacturers of either product discussed below.

Trulicity and Zepbound are both Eli Lilly products, yet they represent two different chapters in incretin science: one a long-established GLP-1-selective agonist, the other a newer dual-agonist. This review sets dulaglutide against tirzepatide on receptor design, approved use, trial record, safety, and cost — then turns to the genetic terrain that applies no matter which a provider chooses. Current as of April 2026.

Two Eli Lilly molecules, two receptor stories

Zepbound (tirzepatide, Eli Lilly) is a GIP/GLP-1 dual agonist. Trulicity (dulaglutide, Eli Lilly) is a GLP-1-selective receptor agonist. For orientation: tirzepatide engages both incretin receptors; semaglutide, liraglutide, and dulaglutide are GLP-1-selective; and retatrutide is an investigational GLP-1/GIP/glucagon triple agonist not FDA-approved as of April 2026. All of these ultimately modulate gastric emptying, post-meal glucose, and satiety signaling.

Where each is FDA-cleared

Approval scope differs by indication. For context across the category: Ozempic (semaglutide) is cleared for type 2 diabetes (2017); Wegovy (semaglutide 2.4 mg) for chronic weight management (2021); Rybelsus (oral semaglutide) for type 2 diabetes (2019); Mounjaro (tirzepatide) for type 2 diabetes (2022); Zepbound (tirzepatide) for chronic weight management (2023) and obstructive sleep apnea (2024, SURMOUNT-OSA); Trulicity (dulaglutide) for type 2 diabetes (2014); and Victoza (liraglutide) for type 2 diabetes (2010). Retatrutide remains investigational.

The trial record, read pairing by pairing

Rather than a single scoreboard, the evidence lives in distinct programs: STEP (semaglutide, weight management), SUSTAIN and SELECT (semaglutide, diabetes and cardiovascular outcomes), SURMOUNT and SURPASS (tirzepatide, weight and diabetes), SURMOUNT-OSA (tirzepatide, sleep apnea), LEAD and LEADER (liraglutide), and AWARD (dulaglutide). Direct comparisons exist for some pairings — SUSTAIN 7 set semaglutide 1 mg against dulaglutide 1.5 mg, and SURPASS-2 set tirzepatide against semaglutide 1 mg in type 2 diabetes. Populations, doses, and endpoints vary, so the honest read is per-trial.

Safety signals they share as a class

Every FDA-approved GLP-1 receptor agonist and GIP/GLP-1 dual agonist carries the class boxed warning for thyroid C-cell tumor risk seen in rodent studies, and all are contraindicated with a personal or family history of medullary thyroid carcinoma or Multiple Endocrine Neoplasia syndrome type 2. Gastrointestinal effects — nausea, vomiting, diarrhea, constipation — are the most common and tend to peak during dose escalation. Rare serious events include pancreatitis, gallbladder disease, and acute kidney injury with dehydration.

What each costs before insurance

As of April 2026, U.S. list prices across the FDA-approved brands span roughly $815 to $1,620 per month (manufacturer published pricing). What you actually pay hinges on insurance coverage, the FDA indication written on the prescription, manufacturer savings-card eligibility, and whether a compounded alternative is available through a licensed compounding pathway.

The genetic terrain both molecules land on

Whichever compound a clinician selects, the upstream architecture is shared. Variants in FTO (fat-mass and obesity-associated gene; influences appetite and adiposity set-point), GLP1R (encodes the GLP-1 receptor every compound here engages), MC4R (a melanocortin receptor central to energy balance), and TCF7L2 (linked to glucose homeostasis and GLP-1 secretion) map the biology a prescription lands in. These are pathway-level markers — they do not predict response to dulaglutide, tirzepatide, or any single molecule.

PlexusDx offers semaglutide and tirzepatide through its Weight Management Protocols; it does not sell, distribute, or prescribe dulaglutide. Regardless of which GLP-1 pathway compound you and your provider discuss, the genetic architecture is the same. The Precision Peptide Genetic Test analyzes 14 pathways, 49 peptides, 150+ genetic insights — including FTO, GLP1R, MC4R, and TCF7L2 variants that shape your baseline GLP-1 and energy-balance biology. That is the test before you invest approach.

Related reading on PlexusDx: Zepbound for Weight Loss, What is Zepbound, Zepbound Cost, Zepbound for Sleep Apnea.

Disclaimer: This is educational content. PlexusDx offers semaglutide and tirzepatide through its Weight Management Protocols and does not sell, prescribe, or recommend dulaglutide. The Precision Peptide Genetic Test analyzes how your genes influence peptide-related pathways and does not predict response to any specific medication. Consult a qualified healthcare provider before beginning any peptide protocol.

Start with your own biology: take the Precision Peptide Genetic Test, or explore the Weight Management Protocols.

Frequently Asked Questions

Are Trulicity and Zepbound the same kind of drug?

Both come from Eli Lilly, but they differ mechanically. Trulicity (dulaglutide) is a GLP-1-selective receptor agonist, while Zepbound (tirzepatide) is a GIP/GLP-1 dual agonist that engages a second incretin receptor. Half-life and dosing also differ, which shapes how each is administered and titrated.

Does head-to-head data favor one over the other?

Direct dulaglutide-versus-tirzepatide trials are limited. SURPASS-2 compared tirzepatide with semaglutide 1 mg in type 2 diabetes and showed larger mean weight reduction with tirzepatide in that study. Weight-management endpoints differ across programs, and individual response varies, so discuss specifics with a provider.

Does the genetic test tell me which molecule will work?

No. The Precision Peptide Genetic Test does not predict response to Trulicity, Zepbound, or any compound. It analyzes pathway-level variants in FTO, GLP1R, MC4R, and TCF7L2 that shape baseline GLP-1 and energy-balance biology — context that applies across both Lilly molecules regardless of which one is prescribed.

Do their side effects differ much?

Profiles are broadly similar across the class, with gastrointestinal symptoms most common and most pronounced during dose escalation. Both carry the class boxed warning for thyroid C-cell tumor risk observed in rodent studies. Rare serious events include pancreatitis and gallbladder disease — review your full history with a provider.

This article is part of the PlexusDx Education Hub. Browse all Peptides & GLP-1 education

Medical and Editorial Standards

Medical review process: This article was reviewed for medical accuracy, scientific clarity, evidence alignment, and appropriate discussion of genetics, medications, supplements, biomarkers, and health-related claims.

Sources and evidence: PlexusDx educational content is developed using peer-reviewed research, clinical literature, reputable medical references, and, where applicable, public health or regulatory guidance. References are included at the end of the article when scientific, medical, or health-related claims are discussed.

Commercial transparency: PlexusDx offers genetic testing, blood biomarker testing, personalized supplement recommendations, and related precision wellness services. Product mentions are intended to help readers understand available options and should not be interpreted as medical advice.

Important disclaimer: PlexusDx educational content is for informational purposes only and should not be used as a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before making decisions about medications, supplements, genetic testing, lab testing, or health-related care.