Dietary quality and carotid intima media thickness in type 1 and type 2 diabetes: Follow-up of a randomised controlled trial

The relationship between dietary intake and carotid intima media thickness (IMT) and pulse wave velocity (PWV) in individuals with type 1 and type 2 diabetes has not been well studied. We investigated the association between dietary intake and common carotid artery intima media thickness (CCA IMT) and PWV in a cohort with type 1 and type 2 diabetes.A one-year randomised controlled trial was conducted to investigate the effect of improving dietary quality on CCA IMT. These subjects were followed up again approximately 12 months after the completion of the trial (i.e. approximately 24 month since baseline). The study cohort included 87 subjects that had dietary intake and CCA IMT measured at baseline and after a mean of 2.3 years' follow-up. PWV was measured in a subsample of this cohort. Age and baseline mean CCA IMT were strongly associated with mean CCA IMT at 24 months. After adjustment for age and baseline mean CCA IMT, baseline consumption of carbohydrate (r = -0.28; p = 0.01), sugars (r = -0.27; p = 0.01), fibre (r = -0.26; p = 0.02), magnesium (r = -0.25; p = 0.02) and the Alternate Health Eating Index (AHEI) score (r = -0.23; p = 0.03) were inversely associated with mean CCA IMT at 24 months. Mixed linear modelling showed an interaction between mean CCA IMT and AHEI at baseline (p = 0.024). Those who were in the highest AHEI tertile at baseline had greater CCA IMT regression at 24 months compared to those in the lowest tertile, after adjustment for baseline age, BMI, smoking pack years, time since diabetes diagnosis, and mean arterial pressure at baseline (mean -0.043 mm; 95% CI -0.084, -0.003; p = 0.029).In this prospective analysis greater diet quality at baseline, as measured by the AHEI, was associated with greater CCA IMT regression after approximately two years. This suggests that greater diet quality is associated with better longer term vascular health in individuals with type 1 and type 2 diabetes.