We found that plasma concentrations of ACE2 were significantly lower in diabetics patients (2973.83 ± 2196.79 pg/mL) than in the non-DM group (4308.21 ± 2352.42 pg/mL) (Figure 1A), which indicated that downregulated ACE2 levels were correlated with impaired glucose homeostasis in patients with diabetes. Here, ACE2 is linked to diabetes mellitus.