Neither the total (sample size: 331 in the GLP-1 receptor agonists group and 230 in the placebo group) nor the subtotal (sample size: 247 and 159 in early PD and 84 and 71 in late PD, in the GLP-1 receptor agonists group and placebo group, respectively) improvements related to GLP-1 receptor agonists were significant (MD = − 1.32; 95% CI − 3.91 to 1.26; p = 0.32 for total comparison) (MD = − 1.11; 95% CI − 4.49 to 2.27; p = 0.52 for early PD subgroup) (MD = − 1.62; 95% CI − 6.70 to 3.45; p = 0.53 for late PD subgroup). The gene discussed is GLP1R; the disease is Parkinson disease.