Specific Aim 1 To recruit 285 type 1 diabetic patients who do not have hypertension, diabetic nephropathy, or predictive levels of microalbuminuria into a 5-year study to determine the effect of inhibition of renin-angiotensin system activity with either losartan (angiotensin II blocker) or enalapril (converting enzyme inhibitor) on the development of diabetic renal disease. This aim has been accomplished and the study is entitled the Renin-Angiotension System Study (RASS).