What is the "incretin effect" of Mounjaro?

By Gwynne Sullivan, Amy Nowacoski · last reviewed May 9, 2026

Adapted from the Mounjaro for Diabetes FAQ with permission from the contributing authors.

The incretin “effect is essential for normal glucose tolerance and is severely compromised in patients with type 2 diabetes. Recent research has documented that new pharmaceutical agents, based on the actions of the two incretin hormones, glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), represent the most effective therapy of the two major metabolic diseases, obesity and type 2 diabetes, improving not only metabolic parameters but also the risks of complications and mortality. … the effect, which is responsible for keeping up to 80% of ingested glucose away from the circulation (2), is essential for normal glucose tolerance. Several compounds are able to influence glucose-stimulated insulin secretion, including several peptides that can be extracted from the intestinal mucosa, but it is generally accepted that the peptides GIP and GLP-1 are the most important responsible factors.” Treatment of Type 2 Diabetes and Obesity on the Basis of the Incretin System: The 2021 Banting Medal for Scientific Achievement Award Lecture ADA Award Lecture, published in Diabetes, 2021 https://diabetesjournals.org/diabetes/article/70/11/2468/123853/Treatment-of-Type-2-Diabetes-and-Obesity-on-the?searchresult=1

“The physiological role of the gastrointestinal tract was traditionally thought to involve nutrient digestion and absorption, but it is now known to be the source of a plethora of peptide hormones involved in the regulation of metabolism and other body functions… two major gastrointestinal tract‐derived hormones involved in regulation of postprandial glucose have been identified, namely, glucagon‐like peptide‐1 (GLP‐1) and glucose‐dependent insulinotropic polypeptide (gastric inhibitory polypeptide; GIP), secreted from L‐cells and K‐cells of the gastrointestinal tract, respectively. Collectively, these two hormones account for 50%–70% of insulin secretion in response to a meal (Baggio & Drucker, 2007), with this action termed ‘the incretin effect’… GLP‐1 receptor mimetic therapy has consistently shown to improve liver disease, possibly indirectly via anti‐inflammatory and weight‐reducing actions…studies highlight the potential of GLP‐1 mimetics for the treatment of diseases and disorders driven by chronic inflammation.” Metabolic responses and benefits of glucagon‐like peptide‐1 (GLP‐1) receptor ligands British Journal of Pharmacology https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8820187/

The evolving story of incretins (GIP and GLP-1) in metabolic and cardiovascular disease: A pathophysiological update Diabetes obesity and Metabolism, July 2021 https://dom-pubs.onlinelibrary.wiley.com/doi/10.1111/dom.14496

The evolving story of incretins (GIP and GLP-1) in metabolic and cardiovascular disease: A pathophysiological update Diabetes Obesity and Metabolism, June 2021 https://dom-pubs.onlinelibrary.wiley.com/doi/10.1111/dom.14496