Nephroprotective effects of nitrendipine in hypertensive type I and type II diabetic patients.

Hypertension is significantly involved in the progression of diabetic nephropathy and in the development of end stage renal disease in both type I and type II diabetes mellitus. We have investigated whether long-term monotherapy with a calcium antagonist, nitrendipine, prevents the development of overt diabetic nephropathy in type I and type II diabetic patients with mild to moderate hypertension and persistent microalbuminuria (ie, incipient nephropathy). After a 4-week run-in and washout period, respectively, 25 patients met the inclusion criteria. Twenty-two patients (six with type I and 16 with type II diabetes) completed the 12-month study. Twelve months of treatment with nitrendipine resulted in a significant reduction in systolic blood pressure in patients with type I (157.5 +/- 8.1 mm Hg v 135.8 +/- 4.2 mm Hg, P < 0.05) and type II (163.1 +/- 4.3 mm Hg v 135.9 +/- 3.6 mm Hg, P < 0.001) diabetes. A significant reduction also was seen in diastolic blood pressure (91.7 +/- 1.7 mm Hg v 79.2 +/- 3.5 mm Hg in type I diabetic patients, P < 0.01; 94.7 +/- 1.4 mm Hg v 78.1 +/- 1.5 mm Hg in type II diabetic patients, P < 0.001). A significant reduction in albuminuria was associated with the blood pressure reduction in both type I (57.8 +/- 11.9 mg/24 hr v 24.9 +/- 5.9 mg/24 hr, -57%) and type II (134.6 +/- 20.7 mg/24 hr v 70.3 +/- 16.8 mg/24 hr, -48%) diabetic patients. The mean glomerular filtration rate increased by 21% (112 +/- 12 mL/min v 135 +/- 14 mL/min) and by 23% (106 +/- 12 mL/min v 130 +/- 14 mL/min) in type I and type II diabetic patients, respectively. No significant changes were found in renal plasma flow rates or in serum concentrations of beta 2-microglobulin. With the exception of a significant (P < 0.05) reduction in hemoglobin A1 concentration in type II diabetic patients after 3 months of treatment with nitrendipine, fasting blood glucose, hemoglobin A1, residual beta-cell function (C-peptide levels), total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides, and body mass index remained essentially unchanged during follow-up. These findings suggest that 12 months of monotherapy with the dihydropyridine-type calcium antagonist nitrendipine reduced albuminuria and increased the lowered glomerular filtration rate without adverse effects on glucose and lipid control.(ABSTRACT TRUNCATED AT 400 WORDS)