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Tirzepatide vs GLP-3 R

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The key difference

Tirzepatide is an approved dual agonist of the GIP and GLP-1 receptors. GLP-3 R is an investigational triple agonist that also activates the glucagon receptor, which is thought to add energy expenditure. Their results come from separate trials rather than a direct comparison, and GLP-3 R is not an approved drug.

Side by side

What it is
TirzepatideA dual GIP and GLP-1 receptor agonist FDA-approved for type 2 diabetes (Mounjaro) and weight management (Zepbound), with weight-loss results that often exceed GLP-1-only agents.
GLP-3 RGLP-3 R is an investigational triple agonist that simultaneously activates the GLP-1, GIP, and glucagon receptors, studied for substantial weight loss and improved glycemic control. It is one of the most potent incretin-based agents in late-stage clinical development.
Research status
TirzepatideClinical
GLP-3 RClinical
Category
TirzepatideWeight & Metabolic
GLP-3 RWeight & Metabolic
Half-life
TirzepatideApproximately 5 days (once-weekly dosing)
GLP-3 RApproximately 6 days, supporting once-weekly dosing
Routes
Tirzepatidesubcutaneous
GLP-3 Rsubcutaneous
Reported dosing
TirzepatideClinical regimens titrate from 2.5 mg weekly up to 15 mg weekly over several months to manage GI tolerability. Stated as labeled clinical dosing.
GLP-3 RResearch-use only and not medical advice; clinical trials escalated doses gradually up to roughly 12 mg subcutaneously once weekly, beginning at much lower starting doses to limit gastrointestinal effects.
Studied for
Tirzepatide
  • Substantial weight loss, often exceeding GLP-1-only agents
  • Strong improvement in glycemic control
  • Dual incretin action (GIP + GLP-1)
  • Improves lipid and metabolic markers
GLP-3 R
  • Produced large mean body-weight reductions in phase 2 trials
  • Triple agonism may raise energy expenditure via glucagon receptor
  • Improves glycemic control and HbA1c in type 2 diabetes studies
  • Reduces hepatic fat content relevant to fatty liver disease
Side effects
Tirzepatide
  • Nausea, vomiting, and diarrhea (especially during titration)
  • Decreased appetite and constipation
  • Risk of pancreatitis (uncommon)
  • Gallbladder issues with rapid weight loss
GLP-3 R
  • Nausea, vomiting, and diarrhea, especially during dose escalation
  • Constipation and reduced appetite
  • Increased heart rate
  • Potential transient rise in fasting glucose at higher doses (glucagon effect)
Cited studies
Tirzepatide4 on its page
GLP-3 R2 on its page

How Tirzepatide works

Tirzepatide is a single peptide that activates both the GIP and GLP-1 incretin receptors. GLP-1 agonism enhances glucose-dependent insulin secretion, suppresses glucagon, slows gastric emptying, and reduces appetite, while GIP agonism is thought to further improve insulin sensitivity and lipid metabolism. This dual incretin action produces robust glycemic and weight effects, with fatty-acid acylation enabling once-weekly dosing.

Full Tirzepatide profile →

How GLP-3 R works

GLP-3 R is a synthetic peptide that acts as a balanced agonist at three receptors: the glucagon-like peptide-1 receptor (GLP-1R), the glucose-dependent insulinotropic polypeptide receptor (GIPR), and the glucagon receptor (GCGR). GLP-1R and GIPR agonism enhance glucose-dependent insulin secretion, slow gastric emptying, and reduce appetite via hypothalamic and brainstem circuits, while glucagon receptor agonism increases energy expenditure and hepatic lipid mobilization. The added glucagon component is thought to drive greater fat oxidation and metabolic rate compared with dual GLP-1/GIP agonists, producing larger reductions in body weight and hepatic fat in clinical trials.

Full GLP-3 R profile →

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