Methods: Utilizing DPP4 and CVD summary statistics from eQTLGen Consortium, GTEx Portal, and UK Biobank, we applied weak IV and pleiotropy robust Mendelian randomization methods (MR-RAPS, GRAPPLE, BESIDE-MR, debiased IVW) and mediation analysis to assess the causal impact of DPP4 at the mRNA level on CVD and the direct effect of DPP4 at the mRNA level on CVD, not mediated by diabetes. This evidence concerns the gene DPP4 and diabetes mellitus.