Metformin regulates the incretin receptor axis via a pathway dependent on peroxisome proliferator-activated receptor-α in mice

Diabetologia. 2011 Feb;54(2):339-49. doi: 10.1007/s00125-010-1937-z. Epub 2010 Oct 23.


Aims/hypothesis: Metformin is widely used for the treatment of type 2 diabetes. Although it reduces hepatic glucose production, clinical studies show that metformin may reduce plasma dipeptidyl peptidase-4 activity and increase circulating levels of glucagon-like peptide 1 (GLP-1). We examined whether metformin exerts glucoregulatory actions via modulation of the incretin axis.

Methods: Metformin action was assessed in Glp1r(-/-), Gipr(-/-), Glp1r:Gipr(-/-), Pparα (also known as Ppara)(-/-) and hyperglycaemic obese wild-type mice with or without the GLP-1 receptor (GLP1R) antagonist exendin(9-39). Experimental endpoints included glucose tolerance, plasma insulin levels, gastric emptying and food intake. Incretin receptor expression was assessed in isolated islets from metformin-treated wild-type and Pparα(-/-) mice, and in INS-1 832/3 beta cells with or without peroxisome proliferator-activated receptor (PPAR)-α or AMP-activated protein kinase (AMPK) antagonists.

Results: In wild-type mice, metformin acutely increased plasma levels of GLP-1, but not those of gastric inhibitory polypeptide or peptide YY; it also improved oral glucose tolerance and reduced gastric emptying. Metformin significantly improved oral glucose tolerance despite loss of incretin action in Glp1r(-/-), Gipr(-/-) and Glp1r(-/-) :Gipr(-/-) mice, and in wild-type mice fed a high-fat diet and treated with exendin(9-39). Levels of mRNA transcripts for Glp1r, Gipr and Pparα were significantly increased in islets from metformin-treated mice. Metformin directly increased Glp1r expression in INS-1 beta cells via a PPAR-α-dependent, AMPK-independent mechanism. Metformin failed to induce incretin receptor gene expression in islets from Pparα(-/-) mice.

Conclusions/interpretation: As metformin modulates multiple components of the incretin axis, and enhances expression of the Glp1r and related insulinotropic islet receptors through a mechanism requiring PPAR-α, metformin may be mechanistically well suited for combination with incretin-based therapies.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Line
  • Diabetes Mellitus, Type 2 / drug therapy
  • Dipeptidyl Peptidase 4 / blood
  • Eating / drug effects
  • Gastric Inhibitory Polypeptide / blood
  • Glucagon-Like Peptide 1 / blood
  • Glucagon-Like Peptide-1 Receptor
  • Hypoglycemic Agents / pharmacology*
  • Hypoglycemic Agents / therapeutic use
  • Male
  • Metformin / pharmacology*
  • Metformin / therapeutic use
  • Mice
  • Mice, Inbred C57BL
  • Mice, Mutant Strains
  • PPAR alpha / genetics
  • PPAR alpha / metabolism*
  • Peptide Fragments / therapeutic use
  • Receptors, Gastrointestinal Hormone / genetics
  • Receptors, Gastrointestinal Hormone / metabolism*
  • Receptors, Glucagon / antagonists & inhibitors
  • Receptors, Glucagon / blood
  • Signal Transduction / drug effects


  • Glp1r protein, mouse
  • Glucagon-Like Peptide-1 Receptor
  • Hypoglycemic Agents
  • PPAR alpha
  • Peptide Fragments
  • Receptors, Gastrointestinal Hormone
  • Receptors, Glucagon
  • exendin (9-39)
  • Gastric Inhibitory Polypeptide
  • Glucagon-Like Peptide 1
  • Metformin
  • gastric inhibitory polypeptide receptor
  • Dipeptidyl Peptidase 4