ACE-INHIBITOR MEDIATED REDUCTIONS IN RENAL SIZE AND MICROALBUMINURIA IN NORMOTENSIVE, DIABETIC SUBJECTS

Recent studies utilizing converting enzyme inhibitors (CEI) in diabetic rats document reductions in both renal hypertrophy and albuminuria. Four separate clinical studies in normotensive patients with diabetes demonstrate reduction of microalbuminuria with CEIs independent of blood pressure reduction. The present pilot study examines the results of reducing an elevated glomerular filtration rate on changes in renal size and microalbuminuria in normotensive, hyperfiltering insulin-dependent diabetic (IDDM) patients. Fifteen IDDM patients were randomized to either placebo or the CEI, lisinopril. Dosage of lisinopril was titrated over 3 months to reduce glomerular filtration rate (GFR) to less-than-or-equal-to 2.33 mL/sec. Evaluation at 18 months demonstrated the lisinopril group had a marked reduction in renal size (16.9 +/- 1.1, baseline versus 12.8 +/- 0.9 cm, 18 months; p < 0.05) and microalbuminuria (92 +/- 11 mug/min, baseline versus 23 +/- 26 mug/min, 18 months; p < 0.05). No change in renal size was noted in the placebo group (15.4 +/- 0.8, baseline versus 14.9 +/- 0.7 cm, 18 months; NS) and albuminuria increased (118 +/- 15 mug/min, baseline versus 293 +/- 32 mug/min, 18 months; p < 0.05). Mean arterial pressure at 18 months was significantly lower in the lisinopril group compared to placebo (102 +/- 4, placebo versus 87 +/- 6 mm Hg, CEI, p < 0.05). This study supports previous animal studies that document reductions in both microalbuminuria and renal size by a CEI. The overall impact of these findings on preservation of renal function cannot be assessed, however, in this short-term study.