GLP-1 Medications Explained: How the Class Works

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 explainer is part of the PlexusDx Education Hub, covering GLP-1 biology, the approved drug class, and the genetics behind metabolic decisions. Browse all Peptides & GLP-1 education.

GLP-1 — glucagon-like peptide-1 — is an incretin hormone your small intestine releases in response to food. It sits at the center of post-meal insulin release, gastric emptying, and satiety, and the GLP-1 receptor agonist drug class mimics its effects on purpose. This article works from the hormone itself out to the medications, the approved compounds as of April 2026, and the genetic variables underneath the whole class.

What native GLP-1 actually is

Native GLP-1 is a 30- to 31-amino-acid peptide secreted by intestinal L-cells. Once released, it stimulates glucose-dependent insulin secretion from pancreatic beta cells, suppresses glucagon, slows gastric emptying, and engages central satiety circuits in the hypothalamus. Its half-life is remarkably short — roughly two minutes — because the enzyme dipeptidyl peptidase-4 (DPP-4) degrades it almost immediately.

How receptor-agonist drugs extend it

GLP-1 receptor agonist medications are engineered to resist DPP-4 degradation, stretching that half-life from minutes into days or even weeks. They bind the same GLP-1 receptor as the native hormone and drive the same downstream effects on insulin secretion, glucagon suppression, gastric emptying, and satiety. Tirzepatide-based compounds add agonism at the GIP receptor — a related incretin receptor — one of the key molecular distinctions in the class.

Which compounds are approved

The FDA-approved GLP-1 receptor agonist class includes exenatide (Byetta, 2005; Bydureon), liraglutide (Victoza, 2010; Saxenda, 2014), dulaglutide (Trulicity, 2014), semaglutide (Ozempic, 2017; Rybelsus, 2019; Wegovy, 2021), and tirzepatide (Mounjaro, 2022; Zepbound, 2023; Zepbound expanded to OSA, 2024). Investigational compounds in late-stage development include retatrutide, a GIP/GLP-1/glucagon triple agonist that is not FDA-approved and not sold by PlexusDx, and orforglipron, an oral non-peptide small-molecule GLP-1 receptor agonist.

How the compounds are administered

Most FDA-approved GLP-1 receptor agonists are given as subcutaneous injections, weekly or daily depending on the compound, while Rybelsus is the sole FDA-approved oral option as of April 2026. Compounded oral GLP-1 protocols exist through licensed compounding pharmacy pathways, but those are not FDA-approved as branded products. For more on the receptor mechanism, see the guide to GLP-1 receptor agonists.

Why genetic context matters

These drugs work by engaging a receptor pathway that carries natural genetic variation. GLP1R — the receptor gene itself, whose variants influence receptor density and incretin signaling efficiency — is the most direct upstream variable. FTO (appetite regulation and adiposity set-point), MC4R (hypothalamic satiety and total energy intake), and TCF7L2 (insulin secretion and incretin response) shape the adjacent biology. These are pathway-level markers describing the terrain any GLP-1 compound has to work on, not predictors of response to a specific one.

Where PlexusDx fits

PlexusDx offers GLP-1 receptor agonists through its Weight Management Protocols. Ahead of any protocol, the Precision Peptide Genetic Test reads 14 pathways, 49 peptides, 150+ genetic insights, including variants in FTO, MC4R, and TCF7L2. It is not a pharmacogenomic test and never predicts drug response — a "test before you invest" step that frames the biology for a more informed provider conversation.

Why this class expanded so fast

Part of what makes the GLP-1 class worth understanding is how quickly it grew from a niche diabetes tool into a broad metabolic category. The progression from the earliest approvals to today's dual and investigational triple agonists reflects steady engineering against a single problem: extending a hormone that the body degrades within minutes into something that can act for days or weeks. Each new compound refines the receptor engagement or adds a second incretin target, and the labeling expands as trials read out. Following that arc helps a reader place any individual product in context rather than treating it as a standalone brand, and it clarifies why genetics upstream of the receptor remain a constant across the whole class. Seen that way, the newest compound and the oldest one are variations on the same biological theme rather than unrelated products.

Frequently Asked Questions

What does GLP-1 stand for?

GLP-1 stands for glucagon-like peptide-1, an incretin hormone secreted by intestinal L-cells in response to food. It stimulates glucose-dependent insulin release, slows gastric emptying, and signals satiety to the brain. The GLP-1 receptor agonist drug class is engineered to mimic these hormonal effects.

Are GLP-1 medications the same as GLP-1 inhibitors?

No — they are opposites. GLP-1 receptor agonists activate the receptor and produce GLP-1 hormonal effects. There is no widely used class called "GLP-1 inhibitors" in current practice. DPP-4 inhibitors are different: they slow breakdown of native GLP-1 but do not activate the receptor directly.

How are GLP-1 receptor agonists taken?

Most FDA-approved GLP-1 receptor agonists are subcutaneous injections, dosed weekly or daily by compound. Rybelsus is the only FDA-approved oral option as of April 2026. Compounded oral protocols exist through licensed compounding pharmacy pathways but are not FDA-approved as branded products.

Does genetic testing tell me which GLP-1 to take?

No. The Precision Peptide Genetic Test does not predict which GLP-1 medication suits any individual. It analyzes pathway-level variants in FTO and MC4R, and other genes that shape baseline GLP-1 biology — context for a broader protocol conversation with a healthcare provider.

Continue at the PlexusDx Education Hub.

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.