he Biostatistics Center served as the biostatistical coordinating center for the trial of angiotensin converting enzyme inhibition (ACEi) in diabetic nephropathy; a multi-center clinical trial of ACEi with captopril in diabetics with chronic renal disease. ACEi in diabetic nephropathy was a double-masked, placebo-controlled randomized clinical trial designed to evaluate the safety and efficacy of ACEi with captopril in retarding the rate of progression of chronic renal disease in insulin dependent diabetes mellitus (IDDM) participants with overt diabetic nephropathy. Over a three-year period in 30 clinical sites in the US and Canada, the ACEi trial randomized a total of 409 participants. Participants were randomized to placebo or ACEi with captopril and followed for two to five years with quarterly visits. The trial concluded that ACEi with captopril protects against deterioration in renal function in IDDM nephropathy and is significantly more effective than blood pressure control alone (The New England Journal of Medicine 1993;329:1456-1462). Funded by NIDDK (R01-DK-39826) and Bristol-Myers Squibb Company, 1987- 1993; IND 12,928.