Moreover, compared with that of the normal control group, the expression of matrix synthesis-related protein (COL2A1) was decreased, while the levels of matrix degradation and inflammatory markers (MMP13, ADAMTS5, TNF-α, IL-6) were increased in the cartilage in the DM group (Supplementary Fig. S1, P < 0.05, P < 0.01). This evidence concerns the gene TNF and diabetes mellitus.