Nitrendipine and enalapril improve albuminuria and glomerular filtration rate in non-insulin dependent diabetes

The effects of 3, 15, and 27 months of treatment with nitrendipine (10 to 40 mg/day) and enalapril (5 to 20 mg/day) on diastolic blood pressure (DBP), overnight urinary albumin excretion (UAE) rate, glomerular filtration rate (GFR), and renal plasma flow (RPF) were studied prospectively in a parallel group design in 13 microalbuminuric non-insulin dependent diabetic patients with mild hypertension and biopsy-proven diabetic glomerulopathy. Throughout the study period DBP decreased in both groups to <95 mm Hg. At three months UAE, GFR, and RPF did not change significantly. At 15 and 27 months UAE (μg/min, geometric mean and 95% C.I.) decreased respectively from 47.4 (23.4 to 95.9) to 28.6 (10.3 to 79.4), and to 22.3 (10.9 to 45.2; P = 0.0005) with nitrendipine, and from 58.3 (30.3 to 110.9) to 44.1 (22.9 to 84.8), and to 14.7 (4.4 to 49.3; P = 0.0025) with enalapril. Four patients in each group were normoalbuminuric at 27 months and none became macroalbuminuric. At 15 months the GFR (ml/min/1.73 m², mean ± SD) increased from 69.5 ± 15.2 to 96.6 ± 22.0 (P <0.05) with nitrendipine and from 58.9 ± 10.7 to 78.5 ± 11.0 (P <0.05) with enalapril. At 27 months the GFR was still numerically higher than at baseline either with nitrendipine (81.2 ± 7.8) and with enalapril (79.9 ± 17.7) (P = 0.7). The RPF (ml/min/1.73 m², mean ± SD) at baseline and at 27 months was comparable either with nitrendipine (456.6 ± 165.3 vs. 400.9 ± 112.9) and with enalapril (400.3 ± 81.3 vs. 399.0 ± 123.7). Both treatments were well tolerated. This is the first evidence that long-term effective control of arterial blood pressure by a calcium channel blocker or by an angiotensin converting enzyme inhibitor, in addition to reducing albuminuria, also improves GFR in incipient nephropathy.