Long-term beneficial effect of ACE inhibition on diabetic nephropathy in normotensive type 1 diabetic patients

Background. The purpose of this study was to assess whether long-term (8 ye ars) inhibition of angiotensin-converting enzyme (ACE) protects kidney func tion in normotensive type 1 diabetic patients with diabetic nephropathy. Methods. We performed an open randomized follow-up study of normotensive ty pe 1 diabetics with nephropathy either treated (N = 15) or not (N = 17) wit h captopril twice per day (average 74, range 12.5 to 125 mg/day). The main outcome measures were arterial blood pressure, albuminuria. and glomerular filtration rate (GFR: Cr-51-EDTA plasma clearance. twice yearly). Results. Arterial blood pressure (mm Hg) was kept constant in the captopril group, at baseline (mean. SEM), 128/75 (3/2) and during follow-up 129/77 ( 4/1) but increased significantly in the control group from 127/79 (2/1) to 137/84 (5/2) (P < ().()I). Furthermore, 8 out of the 17 control subjects re quired treatment with blood pressure-lowering drugs because they developed hypertension. The fractional albumin clearance (x10(-5)) remained unchanged in the captopril group: baseline [10.8 (1.25) geometric mean and antilog ( SEM)1 during the eight years [11.8 (1.47)]. while a significant rise occurr ed in control patients: 13.3 (1.23) to 26.2 (1.42) (P < 0.05). Baseline GFR was nearly identical: 111 (6) and 115 (4) mL/min/1.73 m(2) in the captopri l and control group. respectively. The median (range) rate of decline in GF R (mL/min/year) was 1.7 (10.7 to - 2.0) in the captopril group versus 2.8 ( 17.7 to -2.6) in the control group (P = NS). Conclusions. The beneficial effect of captopril in arresting the rise in sy stemic blood pressure and albuminuria is long lasting. A loss in GFR is min imal in most patients with diabetic nephropathy if normotension is sustaine d by prospective treatment with ACE inhibitors or restored by implementatio n of other antihypertensive medications with the development of hypertensio n.