Briefly, genetic liability to higher levels of CD8+ T cell count (OR = 1.09, 95% CI = 1.03–1.17, p = 0.0053) and CD4+ CD8dim T cell count (OR = 1.04, 95% CI = 1.01–1.08, p = 0.0070) predicted a higher risk of T2D, while genetic liability to lower levels of HLA DR+ NK cell count (OR = 0.98, 95% CI = 0.97–1.00, p = 0.0428) may predict a higher risk of T2D. This evidence concerns the gene CD4 and type 2 diabetes mellitus.