GIP Research History: Discovery, Key Trials and Regulatory Timeline

This page traces what the published literature reports about glucose-dependent insulinotropic polypeptide (GIP), in rough chronological order: how the hormone was first described, how its physiological role was reframed over several decades, and which regulatory events appear in the peer reviewed record. This page is for educational purposes only and is not medical advice; consult a licensed physician for any question about health, medication or treatment. No dosing, protocol or use guidance appears below, and every finding is attributed to the specific paper that reported it.

Discovery: the first incretin hormone to be isolated

Reviews of incretin biology describe GIP as the first of the two classical incretin hormones to be isolated, recovered from intestinal extracts in the early 1970s and named gastric inhibitory polypeptide because of the inhibition of gastric acid secretion observed in those early preparations (PMID 40024571). A 2007 review of incretin biology summarised the subsequent reframing of the molecule: once the glucose-dependent stimulation of insulin release was characterised, the acronym GIP was retained while the expansion was changed to glucose-dependent insulinotropic polypeptide (PMID 17498508).

On the question of individual attribution, the verified literature set used for this page consists of reviews and translational studies rather than the original isolation reports, so no named discoverer is asserted here. What the reviews did establish is the sequence of ideas: a gut peptide identified for one property (gastric effects) was later recharacterised for another (glucose-dependent insulin secretion), and that recharacterisation set the agenda for the next fifty years of GIP research (PMID 40024571, PMID 17498508).

Establishing the incretin concept

The incretin concept holds that nutrients arriving in the gut trigger hormone release that amplifies insulin secretion beyond what an equivalent intravenous glucose load produces. The 2007 Gastroenterology review of incretin biology described GIP and glucagon-like peptide 1 (GLP-1) as the two hormones that account for this effect, and set out their secretion from enteroendocrine cells, their rapid enzymatic degradation and their actions on the pancreatic beta cell (PMID 17498508). That review is a useful anchor point because it captures the state of the field before dual receptor pharmacology became the dominant research direction.

A 2022 review of the enteroendocrine system placed GIP within the wider set of gut hormones studied as targets in obesity research, describing how enteroendocrine signalling has been approached pharmacologically (PMID 35419620). A 2025 review in The Journal of Physiology revisited the same territory with obesity as the organising question and summarised how incretin hormones relate to energy balance as reported across the physiological literature (PMID 39576749).

GIP beyond the pancreas

A recurring theme in later reviews is that GIP receptor expression is not confined to the pancreatic islet. The 2025 Molecular Metabolism review of GIP summarised receptor distribution and the range of tissue level actions that researchers have attributed to GIP signalling, including actions studied outside the beta cell (PMID 40024571). A 2023 Diabetologia review described the field as an expanding incretin universe, covering the movement from basic receptor biology toward clinical translation and the widening list of tissues implicated in incretin action (PMID 36976349).

Preclinical work has continued to add non-pancreatic contexts. A 2024 JCI Insight study reported that GIP receptor signalling alleviated gut inflammation in mice, extending interest in the receptor to intestinal immune and barrier biology (PMID 39723966). That report is an animal study, and the authors framed it within mouse models rather than as a human finding (PMID 39723966).

The agonism versus antagonism question

One of the more unusual features of GIP research is that both activation and blockade of the receptor have been pursued as experimental strategies. The 2023 Diabetologia review discussed this tension directly as part of its account of how incretin biology moved into clinical translation (PMID 36976349), and the 2025 Molecular Metabolism review likewise treated the unresolved direction of GIP receptor modulation as an open scientific question rather than a settled one (PMID 40024571). A 2024 review of mechanisms of action for GLP-1 and dual GIP/GLP-1 receptor agonists summarised the signalling arguments that have been made on each side (PMID 39114288).

The dual agonist era

The pivot from single hormone physiology to engineered multi-receptor peptides is the clearest inflection in the modern GIP timeline. In 2020, a JCI Insight report characterised tirzepatide as an imbalanced and biased dual GIP and GLP-1 receptor agonist, describing pharmacology in which the two receptor activities are not equivalent and in which signalling bias was a defining property (PMID 32730231). That characterisation became a reference point for later discussion of why a dual agonist might behave differently from a selective GLP-1 receptor agonist (PMID 32730231).

A 2023 review in Reviews in Endocrine and Metabolic Disorders compared tirzepatide with GLP-1 analogues across endpoints beyond glycaemia, summarising what the comparative literature reported at that time (PMID 37526853). A separate 2023 review in Diabetes Therapy described tirzepatide as a first-in-class twincretin and discussed the clinical perspectives raised by combining GIP and GLP-1 receptor activity in a single molecule for type 2 diabetes (PMID 37824027). A 2024 review in Frontiers in Endocrinology consolidated the mechanistic account for both GLP-1 and dual GIP/GLP-1 receptor agonists (PMID 39114288).

Triple agonists and the next engineering step

In 2022, a Cell Metabolism paper described LY3437943, a triple agonist at the glucagon, GIP and GLP-1 receptors, and traced the molecule from discovery through to clinical proof of concept for glycaemic control and weight loss (PMID 35985340). That report illustrates how GIP receptor activity moved from being the object of study in its own right to being one component of multi-receptor peptide design (PMID 35985340).

Regulatory timeline as published

The regulatory record that intersects most directly with GIP concerns tirzepatide. A 2022 article in Drugs titled "Tirzepatide: First Approval" reported that tirzepatide, a dual GIP and GLP-1 receptor agonist, received its first approval in the United States in May 2022 for adults with type 2 diabetes (PMID 35830001). No approval of native GIP itself as a medicine appears in the verified literature set used here, and GIP peptide material supplied for laboratory work is generally labelled research use only rather than as a medicine.

Adverse Events: What Studies Report

The verified literature set for this page is weighted toward reviews and mechanistic reports rather than individual safety datasets, so no incidence figures are reproduced here. The 2023 review comparing tirzepatide with GLP-1 analogues discussed tolerability alongside efficacy endpoints as part of its comparison of the two drug classes (PMID 37526853), and the 2023 Diabetes Therapy review of tirzepatide in type 2 diabetes addressed clinical considerations raised by dual incretin receptor pharmacology (PMID 37824027). Regulatory labelling for approved products rather than review articles remains the primary published source for adverse event rates, and the first approval report for tirzepatide in 2022 is the relevant regulatory marker in this set (PMID 35830001). Native GIP is not an approved medicine, and safety characterisation of GIP peptide outside approved dual agonist products is correspondingly limited in this literature (PMID 40024571).

What the record leaves open

• Direction of modulation. Whether GIP receptor agonism or antagonism is the more productive strategy was still presented as unresolved in recent reviews (PMID 36976349, PMID 40024571).
• Contribution within dual agonists. How much of the observed pharmacology of a dual molecule derives from the GIP component remains a mechanistic question, given reports of imbalanced and biased signalling (PMID 32730231, PMID 39114288).
• Non-metabolic tissues. Findings such as the mouse gut inflammation report have not been translated to human outcomes within this set (PMID 39723966).
• Obesity physiology. Reviews continued to refine how incretin signalling relates to energy balance rather than presenting a closed account (PMID 39576749, PMID 35419620).

Related reading

For a background overview of GIP physiology, receptor biology and the terminology used across these papers, see the GIP learn page.

References

• Biology of incretins: GLP-1 and GIP (Gastroenterology, 2007)
• Tirzepatide is an imbalanced and biased dual GIP and GLP-1 receptor agonist (JCI Insight, 2020)
• Targeting the Enteroendocrine System for Treatment of Obesity (Handbook of Experimental Pharmacology, 2022)
• Tirzepatide: First Approval (Drugs, 2022)
• LY3437943, a novel triple glucagon, GIP, and GLP-1 receptor agonist for glycemic control and weight loss: From discovery to clinical proof of concept (Cell Metabolism, 2022)
• The expanding incretin universe: from basic biology to clinical translation (Diabetologia, 2023)
• Beyond glycemia: Comparing tirzepatide to GLP-1 analogues (Reviews in Endocrine and Metabolic Disorders, 2023)
• Challenging Clinical Perspectives in Type 2 Diabetes with Tirzepatide, a First-in-Class Twincretin (Diabetes Therapy, 2023)
• Mechanisms of action and therapeutic applications of GLP-1 and dual GIP/GLP-1 receptor agonists (Frontiers in Endocrinology, 2024)
• Glucose-dependent insulinotropic polypeptide receptor signaling alleviates gut inflammation in mice (JCI Insight, 2024)
• Incretin hormones and obesity (The Journal of Physiology, 2025)
• Glucose-dependent insulinotropic polypeptide (GIP) (Molecular Metabolism, 2025)