Thus, according to Brunner et al., the levels of different populations of EPCs: CPCs (CD34+CD133+), the most primitives EPC subtype; eEPCs (CD34+CD133+CD309+) and ECFCs (CD34+CD133+CD309+CD31+) were all lower in T1DM patients with NPDR but augmented in PDR. Here, CD34 is linked to type 1 diabetes mellitus.