Compared with the HC group, the DKD group exhibited significantly higher levels of CD4+ T cells, the CD4+/CD8+ cell ratio, CD4+ TCM cells (CD3+CD4+CD45RA−CCR7+), and CD8+ TCM cells (CD3+CD8+CD45RA−CCR7+) (all p < 0.05). The gene discussed is CD8A; the disease is diabetic kidney disease.