CFH and diabetes mellitus: CFH was found to be downregulated in the PDR serum as compared to NPDR and controls (PDR vs. no-DM: 0.78 ± 0.12, p = 0.2, PDR vs. NPDR: 0.66 ± 0.07, p = 0.1, NPDR vs. no-DM: 1.205 ± 0.2, p = 0.9) (Figure 3D).