The Aging of Elastic and Muscular Arteries

OBJECTIVE: To compare age-related changes in the mechanical properties of different arterial segments in normal volunteers and subjects with type 2 diabetes. RESEARCH DESIGN AND METHODS: In 169 subjects (diabetic n = 57 and nondiabetic n = 112), we assessed the mechanical properties of three arterial segments of differing wall composition. Pulse wave velocity (PWV) was measured noninvasively in a thoraco-abdominal segment (carotid femoral PWV PWV(cf)), in an upper limb muscular artery (carotid radial PWV PWV(cr)), and from the aorta to the finger (PWV from the aorta to the finger PWV(fin)). Central aortic compliance (CAC) was also measured. RESULTS: Average CAC was lower (0.662 vs. 0.850, P < 0.05) and all measures of PWV tended to be faster in diabetic subjects despite the fact that they were, on average, 10 years younger. However, these measures were not related to age in diabetic subjects. After correcting for blood pressure, only PWV(cf) was associated with age in nondiabetic subjects (P < 0.001). Expressing results as ratios of nonelastic to elastic arterial segments (i.e., PWV(cr)-to-PWV(cf) and PWV(fin)-to-PWV(cf)) improved the relationship with age. Both PWV(cr)-to-PWV(cf) and PWV(fin)-to-PWV(cf) were significantly associated with age in nondiabetic subjects (r = -0.59, P < 0.001; r = -0.57, P < 0.001) but not in diabetic subjects (r = -0.15, P = 0.302; r = -0.24, P = 0.129). Multivariate analysis showed that the ratios were not associated with systolic blood pressure. CONCLUSIONS: There are significant differences in the rate of age-related decline in vascular stiffness in elastic arteries of nondiabetic compared with diabetic arteries. Diabetic arteries appear to age at an accelerated rate at an earlier age and then reach a functional plateau.