ENDOTHELIUM-DEPENDENT AND ENDOTHELIUM-INDEPENDENT VASODILATION OF LARGE ARTERIES IN NORMOALBUMINURIC INSULIN-DEPENDENT DIABETES-MELLITUS

Vascular complications in diabetes mellitus are associated with endoth elial dysfunction. Whether endothelium-dependent vasodilation is impai red in normoalbuminuric patients with insulin-dependent diabetes melli tus (IDDM) is controversial. Using a noninvasive echo-Doppler method, we investigated endothelium-dependent and endothelium-independent vaso dilation in the brachial artery of IDDM patients. There were 52 normoa lbuminuric and normotensive patients with IDDM (aged 31.9+/-9.8 years; diabetes duration, 14.9+/-7.9 years; glycated hemoglobin, 7.9+/-1.2%) and 52 healthy control group (C) subjects comparable for age and sex studied. Brachial artery diameter was measured at baseline, during pos tocclusion reactive hyperemia (flow-mediated, endothelium-dependent di lation [FMD]), and after 400 mu g glyceryl trinitrate (GTN) sublingual ly (endothelium-independent vasodilation). Vasodilation was expressed as the percentage change relative to the baseline diameter. Baseline f low and blood pressure were similar for IDDM patients and C. Baseline vessel diameter was slightly larger in IDDM patients (3.10+/-0.52 mm) compared with C (2.89+/-0.55 mm, P=.05). FMD in IDDM patients was decr eased (12.0+/-9.1% versus 15.7+/-9.5% in C, P=.046), as was GTN-induce d vasodilation (14.9+/-8.2% versus 18.3+/-8.5% in C, P=.045). After co rrection for the difference in baseline diameter, FMD and GTN-induced dilation were not different between the groups. GTN-induced vasodilati on decreased slightly with increasing diabetes duration. There was no relation between the vasodilatory responses and HbAlc. In normo-albumi nuric IDDM patients, endothelium-dependent as well as endothelium-inde pendent vasodilation are normal when the difference in baseline diamet er is taken into account.