Impact of glycemic control on circulating endothelial progenitor cells and arterial stiffness in patients with type 2 diabetes mellitus

BACKGROUND: Patients with type 2 diabetes mellitus (DM) have increased risk of endothelial dysfunction and arterial stiffness. Levels of circulating endothelial progenitor cells (EPCs) are also reduced in hyperglycemic states. However, the relationships between glycemic control, levels of EPCs and arterial stiffness are unknown. METHODS: We measured circulating EPCs and brachial-ankle pulse wave velocity (baPWV) in 234 patients with type 2 DM and compared them with 121 age- and sex-matched controls. RESULTS: Patients with DM had significantly lower circulating Log CD34/KDR(+ )and Log CD133/KDR(+ )EPC counts, and higher Log baPWV compared with controls (all P < 0.05). Among those 120/234 (51%) of DM patients with satisfactory glycemic control (defined by Hemoglobin A1c, HbA1c < 6.5%), they had significantly higher circulating Log CD34/KDR(+ )and Log CD133/KDR(+ )EPC counts, and lower Log baPWV compared with patients with poor glycemic control (all P < 0.05). The circulating levels of Log CD34/KDR(+ )EPC (r = -0.46, P < 0.001) and Log CD133/KDR(+ )EPC counts (r = -0.45, P < 0.001) were negatively correlated with Log baPWV. Whilst the level of HbA1c positively correlated with Log baPWV (r = 0.20, P < 0.05) and negatively correlated with circulating levels of Log CD34/KDR(+ )EPC (r = -0.40, P < 0.001) and Log CD133/KDR(+ )EPC (r = -0.41, P < 0.001). Multivariate analysis revealed that HbA1c, Log CD34/KDR(+ )and Log CD133/KDR(+ )EPC counts were independent predictors of Log baPWV (P < 0.05). CONCLUSIONS: In patients with type 2 DM, the level of circulating EPCs and arterial stiffness were closely related to their glycemic control. Furthermore, DM patients with satisfactory glycemic control had higher levels of circulating EPCs and were associated with lower arterial stiffness.