Carotid Resistance and Pulsatility: Non-Invasive Markers for Diabetes Mellitus-Related Vascular Diseases

Background: Diabetes mellitus (DM) is a major determinant of aging-related vascular diseases. The arterial pulsatility index (PI) and resistance index (RI) are biomarkers of vascular aging. The available data regarding DM with arterial PI and RI are limited. The specific aim of this study was to explore the relationships between DM and the segment-specific PI and RI of the extracranial carotid arteries. Methods: We enrolled 402 DM cases and 3416 non-DM controls from a community-based cohort. Each subject's blood flow velocities in the extracranial common (CCA), internal (ICA), and external (ECA) carotid arteries were measured by color Doppler ultrasonography and used to calculate PIs and RIs. Results: The DM cases had significantly higher age-sex-adjusted means of carotid RIs and PIs than the non-DM controls (all p-values < 0.005). After controlling for the effects of conventional cardio-metabolic risk factors, all carotid RIs and PIs remained significantly correlated with higher odds ratios (ORs) of having DM. The relationships with DM were stronger and more significant for the ECA RI and PI. The multivariable-adjusted ORs were 1.36 (95% confidence interval [CI], 1.21~1.54, p = 3.9 × 10^-7) and 1.30 (95% CI, 1.17~1.45, p = 8.7 × 10^-7) for 1.0 SD increases in the ECA RI and PI, respectively. Compared to the best fit model of conventional cardio-metabolic risk factors, the additions of the ECA RI and PI significantly increased the area under the receiver operating characteristic curve by 0.85% (95% CI, 0.11~1.59%; p = 0.023) and 0.69% (95% CI, 0.01~1.37%; p = 0.046), respectively. Conclusions: This study shows significantly positive associations between DM and carotid RIs and PIs. Carotid RIs and PIs are potential biomarkers for DM-related vascular diseases.