GLP-1 vs GLP-3: What Is GLP-3 and How Do They Compare?

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Quick answer: What is GLP-3?

GLP-3 does not exist. There are only two glucagon-like peptides: GLP-1 and GLP-2. The term "GLP-3" appears in online searches due to confusion, misinformation, or social media posts loosely referring to next-generation weight loss drugs as "third-generation" GLP treatments.

If you are looking for weight loss medication, GLP-1 medications are the proven, FDA-approved option available right now.

The glucagon-like peptide family explained

GLP-1 (Glucagon-Like Peptide-1)

GLP-1 is a 30-amino-acid peptide hormone produced in the gut after eating. It reduces appetite, slows stomach emptying, and improves insulin sensitivity. GLP-1 medications are the most effective weight loss treatments available:

• Semaglutide (Wegovy): ~15% weight loss, once-weekly injection
• Tirzepatide (Zepbound): ~22.5% weight loss, once-weekly injection
• Liraglutide (Saxenda): ~8% weight loss, daily injection
• Orforglipron (Foundayo): ~12% weight loss, daily oral pill (new in 2026)

GLP-2 (Glucagon-Like Peptide-2)

GLP-2 is a 33-amino-acid peptide also produced in the gut. Unlike GLP-1, it promotes intestinal growth, improves nutrient absorption, and repairs the gut lining. It has no effect on weight loss.

• Teduglutide (Gattex): FDA-approved GLP-2 analog for short bowel syndrome
• Used for patients who cannot absorb enough nutrition from their intestines
• Not used for weight loss, diabetes, or appetite control

GLP-3: Does not exist

There is no third glucagon-like peptide. The proglucagon gene produces only GLP-1 and GLP-2 (along with glucagon and other fragments). No "GLP-3" hormone or receptor has been discovered.

GLP-1 vs GLP-2 comparison

What people actually mean by "GLP-3"

When people search for GLP-3, they are usually referring to one of these:

1. Next-generation triple agonists

Retatrutide is a triple-hormone receptor agonist that targets GLP-1, GIP, and glucagon receptors simultaneously. In Phase 2 trials, it produced ~24% weight loss in 48 weeks — more than any current medication. Some social media posts call this "GLP-3" because it is a third-generation weight loss drug, but this is scientifically inaccurate.

• Status: Phase 3 clinical trials (Eli Lilly)
• Expected FDA approval: 2027-2028
• Weight loss: ~24% in Phase 2 trials
• Not available yet — cannot be prescribed or purchased

2. Survodutide (dual glucagon/GLP-1 agonist)

Another next-gen drug targeting both glucagon and GLP-1 receptors. Produced ~19% weight loss in trials. Also sometimes mislabeled as "GLP-3." Currently in Phase 3 trials (Boehringer Ingelheim).

3. CagriSema (semaglutide + cagrilintide)

A combination of semaglutide with an amylin analog. Produced ~22% weight loss in trials. In Phase 3 trials (Novo Nordisk). Not a "GLP-3" but represents the next evolution of GLP-1 therapy.

What is available right now?

While next-generation drugs are promising, they are not available yet. The best option today is current GLP-1 medications:

Bottom line

GLP-3 does not exist. There are only two glucagon-like peptides: GLP-1 (for weight loss and diabetes) and GLP-2 (for intestinal disorders). If you want to lose weight, GLP-1 medications are the proven, FDA-approved option available right now. Next-generation drugs like retatrutide are promising but years away from approval.

Do not wait for a "GLP-3" that may never exist. GLP-1 medications are available today, effective, and more affordable than ever through compounded telehealth programs.