Carotid intima media thickness and ankle brachial index are inversely associated in subjects with and without diabetes.

Carotid intima-media thickness (IMT) and ankle brachial index (ABI) are non-invasive indicators of generalised atherosclerosis. The aim was to determine the association between carotid IMT and ABI in subjects with and without diabetes mellitus (DM), and to analyse specific age change-points. We included 2744 subjects from the Copenhagen City Heart Study (mean age (SD) 56.6 (17.2) years, 56.8% women and body mass index (BMI) 25.4 (4.1) kg/m2). Carotid IMT and ABI measurements were performed during the fifth examination. Of the 2744 subjects, 125 subjects (4.6%) had DM. Average carotid IMT was 0.667 (0.145) mm and ABI was 1.06 (0.14). Subjects with DM were older, had higher BMI and systolic blood pressure (SBP) (all p < .001). Carotid IMT was higher in subjects with DM (0.754 (0.150) mm) compared to subjects without DM (0.662 (0.144) mm) (p < .001), whereas there was no difference in ABI between the two groups. ABI was inversely associated with carotid IMT (slope = -0.17 [-0.207; -0.137] (p < .001). The association remained significant after adjustment for risk factors both in subjects with DM (slope = -0.168 [-0.328; -0.007], p = .040), and in subjects without DM (slope = -0.100 [-0.148; -0.052], p < .001), with a stronger effect of carotid IMT on ABI among subjects with DM. Carotid IMT and ABI were inversely associated in subjects with DM and without DM, but with a stronger effect in subjects with DM. Age and ABI revealed a change-point with a stronger inverse association among subjects aged >60 years.