Quick summary
GIP (Glucose-dependent Insulinotropic Polypeptide) is a 42-amino acid incretin hormone that, together with GLP-1, accounts for 25-70% of the postprandial insulin response. It is one of two receptor targets of tirzepatide (Mounjaro/Zepbound), the highest-efficacy approved obesity drug as of 2026.
Overview
GIP (Glucose-dependent Insulinotropic Polypeptide) is a 42-amino acid incretin hormone secreted by enteroendocrine K-cells in the duodenum and jejunum in response to dietary fat and carbohydrates. Together with GLP-1, GIP accounts for 25–70% of the postprandial insulin response. It is one of the two receptor targets of tirzepatide (Mounjaro/Zepbound), the highest-efficacy approved obesity drug as of 2026.
Mechanism of action
GIP binds the GIPR, a class B GPCR, activating adenylate cyclase (cAMP) and calcium-independent phospholipase A2. In pancreatic beta cells, this potentiates glucose-stimulated insulin secretion (GSIS) while inhibiting glucagon from alpha cells. GIP also acts on adipocytes to promote lipid storage and on bone osteoblasts to regulate bone turnover. Glucose entry via SGLT1 in K-cells triggers KATP channel closure, membrane depolarization, and voltage-gated Ca2+ influx that drives GIP vesicle release.
Dosing protocols
| Purpose | Route | Dosage | Frequency | Notes |
|---|---|---|---|---|
| incretin research (in vitro/animal) | subcutaneous | 10–100 nmol/kg | per study protocol |
Dosing information is for educational purposes only. Consult a qualified healthcare professional before using any peptide.
Research summary
GIP and GLP-1 co-agonism via tirzepatide has demonstrated superior glycemic control and weight loss vs. GLP-1 monotherapy in the SURPASS trials (HbA1c reduction 1.24–2.58%, body weight reduction 5.4–11.7 kg). Research into isolated GIP receptor agonism for obesity is ongoing; paradoxically, GIPR antagonism also produces weight loss, complicating the mechanistic picture. GIPR expression in the CNS and adipose tissue continues to be investigated.[1][2][3][4][5]
Evidence grading
Each claimed benefit is graded by the strength of available evidence. Grades reflect study quality, not effect size.
Strong = multiple RCTs · Moderate = limited trials or observational · Preliminary = animal or in vitro only · Insufficient = anecdotal or no published data
Side effects
Side effects vary by individual. This is not an exhaustive list. Report unusual symptoms to a healthcare professional.
Common stacks
Peptides commonly paired with GIP for synergistic effects.
Legal status
Endogenous GIP and isolated GIP peptide are available for research only. The dual GIP/GLP-1 agonist tirzepatide is FDA-approved (Mounjaro, Zepbound) as a prescription drug. Pure GIP peptide is not approved for human use.
Sourcing & access
Research compound
GIP is classified as a research compound. Regulatory status varies by jurisdiction. Always verify current legal status and source from vendors providing third-party certificates of analysis (COA).
Frequently asked questions
GIP (Glucose-dependent Insulinotropic Polypeptide) is a 42-amino acid incretin hormone secreted by enteroendocrine K-cells in the duodenum and jejunum in response to dietary fat and carbohydrates. Together with GLP-1, GIP accounts for 25 to 70 percent of the postprandial insulin response. It is also one of two receptor targets of tirzepatide (Mounjaro and Zepbound), the highest-efficacy approved obesity drug as of 2026.
Tirzepatide (Mounjaro/Zepbound) is a dual GIP/GLP-1 receptor co-agonist. The SURPASS clinical trial program demonstrated that this co-agonism produces superior glycemic control and weight loss versus GLP-1 monotherapy, with HbA1c reductions of 1.24 to 2.58 percent and body weight reductions of 5.4 to 11.7 kg. The mechanism by which GIP receptor activation amplifies tirzepatide's metabolic effects beyond GLP-1 alone continues to be investigated.
GIP binds the GIPR, a class B GPCR, activating adenylate cyclase to raise intracellular cAMP in pancreatic beta cells. This potentiates glucose-stimulated insulin secretion while inhibiting glucagon from alpha cells. GIP also acts on adipocytes to promote lipid storage and on osteoblasts to regulate bone turnover. Endogenous GIP has a half-life of approximately 7 minutes due to rapid degradation by DPP-4.
Pure GIP peptide is available for research use only and is not FDA-approved for human administration. The dual GIP/GLP-1 agonist tirzepatide is FDA-approved by prescription for type 2 diabetes and obesity. Paradoxically, GIPR antagonism has also been shown to produce weight loss in animal models, complicating the mechanistic picture and suggesting a complex role for the GIP axis in energy homeostasis.
Research references
- Glucose-dependent insulinotropic polypeptide in incretin physiology: role in health and diseaseReview
- Glucose-dependent insulinotropic polypeptide: from pathophysiology to therapeutic opportunities in obesity-associated disordersReview
- The dual glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptor agonist tirzepatide: a novel cardiometabolic therapeutic prospectReview
- Glucose-dependent insulinotropic polypeptide modulates adipocyte lipolysis and reesterificationPubMed
- Glucose-dependent insulinotropic polypeptide induces lipolysis during stable basal insulin substitution and hyperglycaemia in men with type 1 diabetes: a randomized, double-blind, placebo-controlled, crossover clinical trialClinicalTrials.gov