In this study, we collected the recently published genome-wide association study (GWAS) summary-level statistics to investigate the causal relationship between the genetically predicted inhibition of PCSK9 and HMGCR and autoimmune diseases, including SLE, RA, myasthenia gravis (MG), multiple sclerosis (MS), asthma, Crohn’s disease (CD), ulcerative colitis (UC), and type 1 diabetes (T1D), by conducting a drug-targeted MR analysis. This evidence concerns the gene PCSK9 and type 1 diabetes mellitus.