Introduction: Hypertension is associated with increased arterial stiffness. Arterial stiffness, which is a predictor of cardiovascular risk, has been shown to correlate with glycemic control in diabetics. However, it is unclear what is the impact of the recent American Diabetes Association (ADA) 2010 position statement definitions for hemoglobin A1c (HbA1c) on the prediction of arterial stiffness.

Methods: We enrolled 1225 consecutive essential hypertensives (mean age 52.9±11.7 years, 728 males, 86 diabetics). Arterial stiffness was determined with carotid-femoral pulse wave velocity (PWV) using the Complior^® device. HbA1c was measured in venous blood samples.

Results: In multivariable regression analysis, HbA1c exhibited significant positive association with PWV, which was independent of age, gender, mean blood pressure, smoking, body-mass index, blood glucose, LDL and CRP (p<0.001, adjusted R2 of model=0.418). In further analyses we employed dichotomous outcome variable (PWV ≥50th percentile [7.8m/s]). Subjects were divided into 3 groups according to HbA1c levels, based on ADA definitions (Normal group: HbA1c<5.7, Pre-diabetes group: 5.7≤HbA1c≤6.4, Diabetes group: HbA1c≥6.5). In multivariable logistic regression models adjusting for the abovementioned confounders, compared to subjects in the normal group, both the subjects in the pre-diabetes and diabetes group had a significantly elevated odds risk of PWV≥50th percentile (OR=1.653, 95% CI:1.215–2.249, p=0.001 and OR=6.518, 95% CI:1.742–24.381, p=0.005, respectively).

Conclusion: Higher HbA1c is an independent predictor of increased arterial stiffness in never-treated essential hypertensives. Furthermore, our findings support the significance of the cut-off points of the ADA definitions, as they are able to predict increased arterial stiffness and eventually increased cardiovascular risk.