PMID-39951489 – GIP in Incretin Physiology Role in Health and Disease
Campbell JE, Drucker DJ. "Glucose-Dependent Insulinotropic Polypeptide in Incretin Physiology: Role in Health and Disease," Endocr Rev, 2025;46(4):437-467.
Quick Reference
| Property | Value |
|---|---|
| PMID | 39951489 |
| DOI | 10.1210/endrev/bnaf003 |
| Year | 2025 |
| Journal | Endocrine Reviews |
| Study Type | Narrative Review |
| Evidence Level | V |
| Sample | N/A (review) |
| Peptide(s) Studied | GIP |
Key Findings
- GIP (glucose-dependent insulinotropic peptide) is a 42-amino acid incretin hormone secreted from K cells in the proximal small intestine in response to nutrient ingestion
- GIP accounts for approximately 60-80% of the incretin effect (glucose-dependent insulin secretion augmentation after oral vs IV glucose)
- GIP receptor (GIPR) is a class B GPCR expressed on pancreatic beta cells, alpha cells, adipocytes, osteoblasts, and brain regions
- GIP promotes glucose-dependent insulin secretion, inhibits gastric acid, stimulates adipose lipid storage, promotes bone formation, and has neuroprotective effects
- The incretin effect is impaired in type 2 diabetes — GIP's insulinotropic action is blunted (explaining historical skepticism about GIPR agonism as therapy)
- Tirzepatide (GIP/GLP-1 dual agonist) demonstrated that GIPR agonism contributes meaningfully to weight loss and glycemic control beyond GLP-1 alone
- Retatrutide (GIP/GLP-1/glucagon triple agonist) showed even greater weight loss, suggesting additive/synergistic incretin effects
- Paradoxically, both GIPR agonism (tirzepatide) and GIPR antagonism reduce body weight in preclinical models — the mechanism remains debated
Study Design
Comprehensive Endocrine Reviews article covering GIP molecular biology, receptor signaling, tissue-specific actions, role in the incretin effect, pathophysiology in T2D and obesity, and the therapeutic renaissance driven by tirzepatide and retatrutide.
Limitations
- Review article; no new primary data
- The GIPR agonism vs antagonism paradox for weight loss remains incompletely resolved
- Long-term cardiovascular and cancer safety data for GIPR-targeting drugs still accumulating
- GIP's role in adipose tissue remains controversial (lipogenic vs lipolytic depending on metabolic state)
Clinical Relevance
This 2025 Endocrine Reviews article represents the most current comprehensive synthesis of GIP biology, written in the context of tirzepatide's clinical success. For the vault, it provides essential mechanistic context for why tirzepatide (GIP/GLP-1 dual) and retatrutide (GIP/GLP-1/glucagon triple) produce superior weight loss compared to GLP-1-only agonists like semaglutide. Understanding GIP physiology is critical for Module 5 (Weight Loss & Body Composition Management) and for explaining the rationale behind multi-receptor incretin therapeutics.
Related
#research #narrative-review #evidence-level-V #metabolic #GIP #endogenous #incretin