Oral glucose loading acutely attenuates endothelium-dependent vasodilation in healthy adults without diabetes: an effect prevented by vitamins C and E

J Am Coll Cardiol. 2000 Dec;36(7):2185-91. doi: 10.1016/s0735-1097(00)00980-3.


Objectives: The goal of this study was to determine whether postprandial hyperglycemia, induced by oral glucose loading, attenuates endothelial function in healthy subjects without diabetes and whether coadministration of vitamins C and E could prevent these postprandial changes.

Background: Epidemiologic evidence suggests that postprandial hyperglycemia, below diabetic levels, is a risk factor for cardiovascular disease. Postprandial hyperglycemia may promote atherosclerosis through endothelial dysfunction and oxidative stress.

Methods: We evaluated the acute effects of oral glucose loading (75 g), alone and with vitamins C (2 g) and E (800 IU), on endothelium-dependent flow-mediated dilation (FMD) of the brachial artery, in a randomized, double-blind, placebo-controlled, crossover study of 10 healthy volunteers. Changes in the levels of markers of oxidative stress (plasma malondialdehyde and erythrocyte glutathione, glutathione peroxidase and superoxide dismutase) were also assessed.

Results: Increases in plasma glucose and insulin after glucose loading were unaffected by vitamin coadministration. With glucose loading alone, FMD fell from 6.5+/-2.2 at baseline to 5.4+/-1.7, 3.7+/-2.1*, 4.1+/-3.5* and 5.7+/-1.9% at 1, 2, 3 and 4 h (*p < 0.05 vs. 0 h). In contrast, FMD did not change significantly after glucose plus vitamins (6.4+/-1.3, 7.6+/-1.8, 7.9+/-2.7, 6.9+/-2.3, 6.9+/-1.9% at 0, 1, 2, 3 and 4 h). By two-way repeated measures analysis of variance we found a significant interaction between vitamin treatment and time (p = 0.0003), indicating that vitamins prevented the glucose-induced attenuation of FMD. Oxidative stress markers did not significantly change with glucose loading alone or with vitamins.

Conclusions: Oral glucose loading causes an acute, transient decrease of FMD in healthy subjects without diabetes, which is prevented by vitamins C and E.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Ascorbic Acid / therapeutic use*
  • Cross-Over Studies
  • Double-Blind Method
  • Endothelium, Vascular / physiology*
  • Female
  • Humans
  • Hyperglycemia / physiopathology*
  • Hyperglycemia / prevention & control*
  • Male
  • Oxidative Stress
  • Postprandial Period / physiology*
  • Vasodilation / physiology*
  • Vitamin E / therapeutic use*


  • Vitamin E
  • Ascorbic Acid