In this study, we collected data on patient demographics, disease characteristic, and the absolute numbers and proportions of peripheral lymphocytes, especially CD4+ T subsets, of patients with RA and DM and those with RA but without DM (RA-T2D and RA-N-T2D, respectively), and analyzed the factors influencing the occurrence of DM in patients with RA. This evidence concerns the gene CD4 and rheumatoid arthritis.