Introduction: Vascular endothelial dysfunction, accelerated thickening of arterial intima and changes in ventricular repolarization contribute to increased cardiovascular morbidity in type 1 diabetes (T1D). Although vitamin C has important antioxidant functions, and increased oxidative stress is a central mechanism of cardiovascular dysfunction in T1D, the relationship between vitamin C and cardiovascular system in young diabetic patients has not been yet investigated.
Methods: Carotid artery intima-media thickness (cIMT), cutaneous microvascular responses to endothelium-dependent (acetylcholine, Ach) and independent (sodium nitroprusside, SNP) agonists, and QTc interval were measured in 59 patients (mean age: 17, range: 10-22 years) with T1D (mean diabetes duration: 9, range: 3-20 years). Plasma vitamin C was analyzed by high-performance liquid chromatography with coulometric detection.
Results: cIMT and QTc were increased in patients in the lowest tertile of vitamin C compared to those in the highest tertile (p=0.04 for both). Also, in the lowest tertile group, cutaneous microvascular response to Ach was decreased (p=0.003), while the response to SNP was similar compared to patients from the highest tertile group. All differences remained significant after adjustment for age, diabetes duration, body mass index, and HbA1c.
Conclusion: In juvenile T1D, lower plasma levels of vitamin C are associated with adverse changes in microcirculation, peripheral arteries and ventricular repolarisation. Further studies are needed to investigate whether dietary supplementation with vitamin C in young patients with T1D could improve these changes, and retard the development of cardiovascular complications later in life.