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GLP-1 (glucagon-like peptide-1) is a natural gut hormone that regulates blood sugar and appetite -- and the drug class that mimics it has transformed diabetes and weight loss treatment.
GLP-1 (glucagon-like peptide-1) is a natural gut hormone that regulates blood sugar and appetite -- and the drug class that mimics it has transformed diabetes and weight loss treatment.
GLP-1 has become a household abbreviation. Most people who encounter it know it has something to do with Ozempic, weight loss, or diabetes -- but not what the hormone actually is, what it does in a healthy body, or why pharmaceutical companies spent decades trying to copy it. The gap between media saturation and patient understanding is wide, and it costs people time when they need to make real decisions about treatment.
Glucagon-like peptide-1 is a hormone your small intestine produces every time you eat. Specialized L-cells release it into the bloodstream within minutes of a meal. It tells your pancreas to make insulin, tells your brain you're full, and slows digestion so glucose enters your blood gradually. GLP-1 receptor agonist medications mimic this process -- but stronger, and for far longer than the body's own supply lasts.
This guide is for anyone trying to understand GLP-1: people with type 2 diabetes weighing medication options, people exploring weight-loss treatments, or people who keep seeing the acronym and want the actual science. For a broader overview of all GLP-1 medications, access pathways, and cost information, visit our GLP-1 hub.
Your digestive system does more than break down food. It sends hormonal signals. GLP-1 is one of two primary incretin hormones (the other is GIP, or glucose-dependent insulinotropic polypeptide). Together, they drive roughly 50-70% of the insulin your body releases after a meal.
Natural GLP-1 does five things:
Your body's own GLP-1 has a half-life of about 2 minutes. An enzyme called DPP-4 destroys it almost immediately. The hormone works as a brief, meal-triggered pulse -- not a sustained metabolic signal.
That rapid breakdown is exactly what drug developers set out to overcome.
GLP-1 receptor agonists (GLP-1 RAs) are synthetic molecules that bind to the same receptors as natural GLP-1 but resist DPP-4 degradation. They produce the same effects -- insulin stimulation, glucagon suppression, delayed gastric emptying, appetite reduction -- at higher concentrations and for far longer.
The first GLP-1 RA, exenatide (Byetta), reached the market in 2005. It was derived from a compound in Gila monster saliva -- the lizard naturally produces a GLP-1-like molecule that DPP-4 cannot break down. The class has since moved from twice-daily injections to once-weekly formulations and expanded from diabetes treatment into chronic weight management.
Previous weight loss drugs worked through riskier mechanisms:
GLP-1 RAs work through a pathway your body already uses. They don't stimulate the central nervous system or block nutrient absorption. Large trials have shown cardiovascular benefits rather than risks. That is a fundamentally different safety profile.
For a detailed comparison, see our GLP-1 comparison tool.
Every currently FDA-approved GLP-1 receptor agonist and dual agonist, with brand names, approved indications, dosing, and route:
| Active Ingredient | Brand Name(s) | Drug Class | FDA-Approved Indications | Dosing Frequency | Route |
|---|---|---|---|---|---|
| Semaglutide 0.5mg, 1mg, 2mg | Ozempic | GLP-1 RA | Type 2 diabetes | Once weekly | Subcutaneous injection |
| Semaglutide 2.4mg | Wegovy | GLP-1 RA | Chronic weight management; cardiovascular risk reduction in overweight/obese adults | Once weekly | Subcutaneous injection |
| Semaglutide 3mg, 7mg, 14mg | Rybelsus | GLP-1 RA | Type 2 diabetes | Once daily | Oral tablet |
| Tirzepatide 2.5mg-15mg | Mounjaro | GLP-1/GIP dual agonist | Type 2 diabetes | Once weekly | Subcutaneous injection |
| Tirzepatide 2.5mg-15mg | Zepbound | GLP-1/GIP dual agonist | Chronic weight management | Once weekly | Subcutaneous injection |
| Liraglutide 1.2mg, 1.8mg | Victoza | GLP-1 RA | Type 2 diabetes; cardiovascular risk reduction | Once daily | Subcutaneous injection |
| Liraglutide 3.0mg | Saxenda | GLP-1 RA | Chronic weight management | Once daily | Subcutaneous injection |
| Dulaglutide 0.75mg-4.5mg | Trulicity | GLP-1 RA | Type 2 diabetes; cardiovascular risk reduction | Once weekly | Subcutaneous injection |
| Exenatide | Byetta | GLP-1 RA | Type 2 diabetes | Twice daily | Subcutaneous injection |
| Exenatide extended-release | Bydureon BCise | GLP-1 RA | Type 2 diabetes | Once weekly | Subcutaneous injection |
| Albiglutide | Tanzeum (discontinued) | GLP-1 RA | Type 2 diabetes | Once weekly | Subcutaneous injection |
Note on tirzepatide: Mounjaro and Zepbound are dual GLP-1/GIP receptor agonists, not pure GLP-1 drugs. The dual mechanism likely explains their higher efficacy in clinical trials.
For detailed profiles: Ozempic, Wegovy, Mounjaro, Zepbound.
Four decades from discovery to blockbuster:
The American Diabetes Association now recommends GLP-1 RAs as a preferred second-line therapy after metformin, especially for patients with established cardiovascular disease or high cardiovascular risk. They lower A1C by 1.0-1.8 percentage points on average. Semaglutide and tirzepatide consistently show the largest reductions in head-to-head trials.
FDA-approved weight management indications cover adults with:
These medications are prescribed alongside dietary changes and increased physical activity.
Wegovy (semaglutide 2.4mg), Victoza, and Trulicity have all demonstrated cardiovascular benefits in large outcomes trials -- reductions in heart attack, stroke, and cardiovascular death.
Learn more about GLP-1 insurance coverage and access.
GI side effects are the main barrier. They typically peak during dose escalation and ease over weeks.
Gradual dose titration -- starting low and increasing slowly -- is the standard approach to reduce GI symptoms. Most patients tolerate the medication after the first few weeks.
Discuss your complete medical history with your provider before starting any GLP-1 medication.
Adults with type 2 diabetes who haven't achieved adequate blood sugar control through lifestyle changes or metformin alone. GLP-1 RAs are not approved for type 1 diabetes.
For details on GLP-1 cost and affordability, including manufacturer savings programs and insurance, see our cost guide.
The class is moving fast. The key tradeoffs to watch:
Explore our complete GLP-1 resource hub for medication comparisons, cost guides, insurance coverage, and access pathways.
This article is for informational purposes only and does not constitute medical advice. Consult your healthcare provider before starting, stopping, or changing any medication.
This information is educational and does not replace professional medical or legal advice.
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