GLP-1 and ghrelin act as a yin-and-yang pair — one rising after meals to boost insulin and suppress hunger, the other rising before meals to inhibit insulin and drive appetite — creating a coordinated system for metabolic control.
3 sites of opposing actionGLP-1 and ghrelin inversely regulate insulin at pancreatic beta cells, vagal afferents, and hypothalamic arcuate nucleus neurons
What the researchers found
GLP-1 and ghrelin act as opposing regulators of the insulin system at three key levels: pancreatic beta cells (GLP-1 stimulates insulin release, ghrelin suppresses it), vagal afferent neurons, and hypothalamic arcuate nucleus neurons. Critically, their timing is complementary — ghrelin rises and acts before meals while GLP-1 rises and acts after meals. This preprandial/postprandial interplay with insulin creates an integrated circadian control system for appetite, blood sugar, and metabolism.
Why it matters
Understanding how GLP-1 and ghrelin work together — not just individually — explains why drugs targeting either hormone can have such broad metabolic effects. It also suggests that future therapies manipulating both pathways simultaneously could achieve more precise control of appetite and blood sugar.
How the study worked
Narrative review integrating evidence from cellular studies in pancreatic beta cells, neurophysiology of vagal afferents and hypothalamic arcuate nucleus neurons, and hormonal signaling research across animal and human studies.
Who was studied
Review of basic science and translational research on GLP-1, ghrelin, and insulin interactions across cellular, neural, and whole-organism levels
What this study cannot tell us
As a review, this synthesizes existing research rather than presenting new data. Much of the mechanistic detail comes from animal models (particularly mice). The described interplay between GLP-1, ghrelin, and insulin is a framework for understanding, not a complete model — other hormones and neural pathways also participate.
How to read the evidence
Rated moderate because this review synthesizes well-established cellular and physiological research, but the integrated framework describing GLP-1/ghrelin interplay is partly theoretical and draws heavily on animal model data.
When this study was published
Published in 2025, this is a current review that integrates decades of research into a unified framework. Highly relevant given the surge of interest in GLP-1-based therapies.
The bigger picture
Drugs targeting GLP-1 (semaglutide, tirzepatide) are transforming obesity and diabetes treatment, while ghrelin-targeting drugs (like MK-677) are used to stimulate growth hormone. Understanding that these two peptide systems are fundamentally interconnected — not isolated pathways — could inform the next generation of metabolic drugs and explain why GLP-1 drugs affect so many aspects of metabolism beyond weight loss.
Questions still open
- Could drugs that simultaneously enhance GLP-1 signaling and suppress ghrelin produce even greater metabolic benefits than targeting either alone?
- Does the disruption of ghrelin-GLP-1 circadian timing contribute to metabolic dysfunction in shift workers?
- How does ghrelin resistance in obesity affect this reciprocal relationship with GLP-1?
Common questions
How do GLP-1 and ghrelin work together to control hunger?
Why does this matter for understanding GLP-1 drugs like Ozempic?
Read the original research
GLP-1 and ghrelin inversely regulate insulin secretion and action in pancreatic islets, vagal afferents, and hypothalamus for controlling glycemia and feeding.
American journal of physiology. Cell physiology, 328(6), C1793-C1807
Citation
Yada, Toshihiko; Dezaki, Katsuya; Iwasaki, Yusaku. (2025). GLP-1 and ghrelin inversely regulate insulin secretion and action in pancreatic islets, vagal afferents, and hypothalamus for controlling glycemia and feeding.. American journal of physiology. Cell physiology, 328(6), C1793-C1807. https://doi.org/10.1152/ajpcell.00168.2025