The effect of acute hyperglycaemia on brachial artery flow mediated dilatation in normal volunteers

Background: Endothelial function is known to be abnormal in patients with d iabetes and acute hyperglycaemia may play an aetiological role. Aims: The aim of this randomised controlled study was to determine if acute systemic hyperglycaemia impairs endothelial function in normal subjects. Methods: Endothelial function was assessed by the change in brachial artery diameter in response to forearm ischaemia using B-mode ultrasound in ten h ealthy subjects (eight male) aged 19-35 years. Brachial artery blood now ve locity and diameter were measured before and after five minutes of forearm ischaemia. Measurements were performed in the supine position after an over night fast, before and after 60 minute infusions of 0.9% saline or 10% dext rose. Measurements were made on two separate occasions at least 24 hours ap art, and subjects wen randomised to saline first or dextrose first. The lar gest diameter measured after ischaemia was divided by the resting arterial diameter to calculate percent dilatation of the artery from baseline, and i s reported as flow-mediated dilatation (FMD). Results: Dextrose infusion resulted in a significant rise in mean (SD) seru m glucose 5.2 (0.1) to 9.2 (0.3) mmol/L and insulin concentration 6.3 (1.4) to 20.6 (3.7) mU/Lp<0.002. Brachial artery blood flow velocity and diamete r increased significantly from baseline after ischaemia (p<0.002). Mean FMD (SEM) before and after infusion were not, however, significantly different (p=0.4) (pre-saline 7.3 [1.0]%, post saline 5,2 [1.5]% and predextrose 8.1 [2.0]%, post dextrose 5.9 [1.7]%). Conclusions: These data suggest that acute hyperglycaemia does not impair F MD in normal subjects.