Poor vitamin C status is associated with increased carotid intima-media thickness, decreased microvascular function, and delayed myocardial repolarization in young patients with type 1 diabetes.
BACKGROUND
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 relation between vitamin C and the cardiovascular system in young diabetic patients has not been investigated.


OBJECTIVE
In a cohort of young patients with T1D, we investigated the relation of plasma concentrations of vitamin C with indexes of vascular function and structure and duration of the QT interval corrected for heart rate (QT(c)).


METHODS
Carotid artery intima-media thickness, cutaneous microvascular function, and duration of the QT(c) interval were measured in 59 patients (mean age: 17 y; range: 10-22 y) with T1D (diabetes duration: 3-20 y). Plasma vitamin C was analyzed by HPLC with coulometric detection.


RESULTS
Carotid artery intima-media thickness and duration of the QT(c) interval were higher in patients in the lowest tertile of vitamin C than in those in the highest tertile (P < 0.05 for both). The cutaneous microvascular response to acetylcholine was lower (P = 0.003) in the lowest tertile group than in the highest tertile group, but the response to sodium nitroprusside was not significantly different between these 2 groups. All differences remained significant after adjustment for age, sex, diabetes duration, body mass index, and glycated hemoglobin.


CONCLUSIONS
In this relatively small-scale cross-sectional study of young patients with T1D, lower plasma concentrations of vitamin C seem to be associated with adverse changes in the microcirculation, peripheral arteries, and ventricular repolarization. Large-scale prospective studies are needed to confirm these results and to clarify the underlying mechanisms.
Odermarsky
Michal
M
Division of Pediatric Cardiology, Department of Pediatrics, Lund University Hospital, 221 85 Lund, Sweden.
Lykkesfeldt
Jens
J
Liuba
Petru
P
D000293:Adolescent; D001205:Ascorbic Acid / Q000097:blood*; D002339:Carotid Arteries / Q000473:pathology*; D002648:Child; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D003922:Diabetes Mellitus, Type 1 / Q000097:blood / Q000473:pathology / Q000503:physiopathology*; D004730:Endothelium, Vascular / Q000473:pathology* / Q000502:physiology; D005260:Female; D006442:Glycated Hemoglobin / Q000378:metabolism; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008833:Microcirculation / Q000502:physiology; D009752:Nutritional Status; D012867:Skin / Q000098:blood supply; D017539:Tunica Intima / Q000473:pathology; D017540:Tunica Media / Q000473:pathology; D055815:Young Adult
D001205:Ascorbic Acid; D006442:Glycated Hemoglobin