After removing unmatched genes, the results showed that two genes [including transferrin receptor (TFRC) and solute carrier family-11 member-2 (SLC11A2)] were both significantly down-regulated in T2DM samples when compared with normal samples, indicating that the downregulation of two key genes might cause IO and further induce the occurrence of T2DM (Fig. 7). The gene discussed is TFRC; the disease is type 2 diabetes mellitus.