The degree of endothelial dysfunction in young adults with type 1 diabetes positively correlates with CD34+CD133+CD31+ cells in the peripheral blood. Vascular reactivity was evaluated using a laser Doppler iontophoresis methodology. A, Endothelium-dependent function was assessed by measuring vasodilation in response to 6 repeated stimulations with acetylcholine (Ach), n = 17 per group,* P < .05. B, Endothelium-independent function was assessed by measuring vasodilation in response to 6 repeated stimulations with nitroprusside (SNP), n = 17 control subjects, n = 16 subjects with diabetes. C, Correlation between CD34+CD133+CD31+ cells and maximal vasodilation after iontophoretic stimulation with acetylcholine was examined for the subjects with diabetes, * P < .05.