rs3765467 — GLP1R Arg131Gln

GLP1R Arg131Gln — A Receptor Variant That Reshapes GLP-1 Drug Response

The GLP-1 receptor¹¹ GLP-1 receptor
Glucagon-like peptide-1 receptor, the molecular target of Ozempic, Wegovy, and Saxenda is the direct drug target for some of the most prescribed medications in modern medicine: semaglutide (Ozempic, Wegovy), liraglutide (Saxenda, Victoza), and exenatide (Byetta). Unlike most pharmacogenomic variants that affect drug metabolism enzymes, rs3765467 changes the drug target itself — replacing arginine with glutamine at position 131 in the receptor's extracellular binding domain. This variant is strikingly population-specific: carried by about 21% of East Asians but fewer than 0.3% of Europeans.

The Mechanism

Position 131 sits in exon 4 of GLP1R²² exon 4 of GLP1R
The extracellular N-terminal domain where GLP-1 and its drug analogues make initial contact with the receptor, within the ligand-binding pocket that makes direct contact with GLP-1 and its pharmaceutical mimics. Arginine at this position carries a positive charge that participates in electrostatic interactions stabilizing ligand binding. The glutamine substitution removes this charge, altering receptor conformation and downstream cAMP signaling³³ cAMP signaling
Cyclic adenosine monophosphate, the key second messenger that triggers insulin release from pancreatic beta cells. In beta-cell models, the variant receptor shows significantly reduced glucose-stimulated insulin secretion and increased apoptosis⁴⁴ significantly reduced glucose-stimulated insulin secretion and increased apoptosis
Li et al. GLP1R SNPs rs3765467 and rs10305492 affect beta-cell insulin secretory capacity. DNA Cell Biol, 2020. However, in living human carriers, the picture is paradoxically reversed — healthy heterozygotes show over 100% greater beta-cell responsivity to GLP-1⁵⁵ healthy heterozygotes show over 100% greater beta-cell responsivity to GLP-1
Sathananthan et al. Common genetic variation in GLP1R and insulin secretion. Diabetes Care, 2010, suggesting compensatory mechanisms that amplify the signal in vivo.

The Evidence

The strongest genetic evidence comes from a large East Asian exome-wide study⁶⁶ large East Asian exome-wide study
Kwak et al. Nonsynonymous variants in PAX4 and GLP1R are associated with type 2 diabetes. Diabetes, 2018 of over 17,000 individuals, which showed the A allele is protective against type 2 diabetes at genome-wide significance (OR 0.84, P = 3.55 x 10^-8). This is consistent with the enhanced insulin secretion seen in carriers.

For drug response, two key findings stand out. A Korean pharmacogenomic study⁷⁷ Korean pharmacogenomic study
Han et al. A genetic variant in GLP1R is associated with response to DPP-4 inhibitors. Medicine, 2016 of 246 T2D patients found A allele carriers had twice the odds of responding to DPP-4 inhibitors (OR 2.00, 95% CI 1.03-3.89), with greater HbA1c reduction (1.3% vs 0.9%, P = 0.022). In contrast, a Chinese prospective cohort⁸⁸ Chinese prospective cohort
Guan et al. Association between GLP1R gene polymorphism and treatment response to GLP1R agonists. Eur J Clin Pharmacol, 2022 of 156 patients found the wild-type GG genotype had significantly better HbA1c reduction on GLP-1 agonists (1.7% vs 0.8%, P = 0.002) and higher rates of reaching target HbA1c (50.9% vs 23.8%).

This apparent contradiction likely reflects different drug mechanisms: DPP-4 inhibitors raise endogenous GLP-1 to physiological levels (where the variant receptor's enhanced sensitivity is advantageous), while GLP-1 agonists deliver pharmacological doses that may overwhelm the altered receptor. Supporting this, A allele carriers also show increased gastrointestinal side effects on liraglutide⁹⁹ increased gastrointestinal side effects on liraglutide
Long et al. Eur J Clin Pharmacol, 2022 (P = 0.007), with a dose-dependent relationship between A allele count and nausea severity.

Practical Implications

The core clinical question for carriers is which GLP-1-based therapy will work best. The evidence suggests that if the primary goal is glycemic control, DPP-4 inhibitors (sitagliptin, saxagliptin) may be more effective than expected for A allele carriers. If a GLP-1 agonist (semaglutide, liraglutide) is chosen — particularly for weight loss — slower dose titration and close monitoring of both gastrointestinal tolerance and glycemic response are warranted.

Interactions

The parallel GLP1R variant rs6923761 (Gly168Ser) also modifies GLP-1 agonist response but through a distinct mechanism — primarily affecting gastric emptying rate and weight loss magnitude. Carriers of both Arg131Gln and Gly168Ser may have compounded alterations in GLP-1 agonist response affecting both glycemic control and weight loss. The related GIPR variant rs10423928 affects the parallel incretin pathway and may further modify response to dual GIP/GLP-1 agonists like tirzepatide (Mounjaro). The intracellular GLP1R variant rs10305492 (Ala316Thr) also reduces beta-cell signaling and may compound with Arg131Gln to create a more severely impaired receptor profile.