ATP6AP1 and diabetes mellitus: All the hub proteins (ALB, FN1, ACTB, SERPINA1, C3, and VTN) and the two biomarker combinations proteins (SIAE, SEMA7A, GNS, IGKV3D-15, ATP6AP1, SPARCL1, and SERPINA7) showed a significant correlation with the duration of diabetes (Fig. 4B, p = 0.001, p = 0.019, p = 0.006, p < 0.001, p = 0.001, p = 0.002, p < 0.001, p < 0.001, p < 0.001, p = 0.003, p = 0.001, p < 0.001, and p < 0.001, respectively).