In nutshell, we identified seven hub genes (HIST2H2AA3, HIST2H2AA4, NFKBIA, SESN2, SMURF1, TGFβ1, TNRC6A) in T2DM vs. PC, six common hub genes (ATP6V0D1, ATP6V0C, ATP6V0E1, CTSD, CYBA, TGFβ1) in T2DM vs. LC and five common hub genes (ALYREF, CDKN2D, NGDN, THRAP3, UBE2M) in T2DM vs. BC, respectively (Fig. 3). This evidence concerns the gene CTSD and breast cancer.