Upregulated genes in CD8+ T cells of T1DM patients included cytotoxicity-associated genes, such as PRF1, GZMH, ITGB2, NKG7, CTSW, and CST7, whereas the expression of CD4, CD7, CD5, HLA-A, CD27, and IL-32 was downregulated. Here, PRF1 is linked to type 1 diabetes mellitus.