The purpose of the current study is therefore aimed at demonstrating that it is possible to prevent kidney disease in patients with type 1 diabetes and normal office blood pressure and urine protein excretion by selecting them on the basis of an abnormal fall in blood pressure at night. Moreover, this clinical trial will reveal the impact of long-term administration of an ACE inhibitor on nighttime blood pressure and also assess changes in the relative stiffness of blood vessels(endothelial dysfunction) in persons with type 1 diabetes over time.