Renoprotective effect of diltiazem in hypertensive type 2 diabetic patients with persistent microalbuminuria despite ACE inhibitor treatment

Abstract

The aim of the study was to evaluate the effects of the non-dihydropyridine calcium antagonist (NDCA) diltiazem on the development of urinary albumin excretion (UAE) in type 2 hypertensive diabetic patients with persistent microalbuminuria despite ACE inhibitor treatment. Thirty-six type 2 diabetic hypertensive patients with microalbuminuria persisting after at least 1 year of treatment with ACE inhibitors were randomized to receive captopril ( n = 22) or combined therapy with captopril and 120 mg diltiazem ( n = 14) for 2 years. Captopril dose was individualized according to blood pressure. Changes in UAE, blood pressure, and metabolic control were monitored to analyze the influence of the addition of diltiazem on progression of diabetic nephropathy. In patients treated with captopril and diltiazem, absolute UAE did not change during the study (baseline: 101 mg/24 h, range 39–298; 2 years after randomization: 74 mg/24 h, range 12–665). In contrast, UAE increased in patients treated with captopril monotherapy (baseline: 118 mg/24 h, range 32–282; 2 years after randomization: 164 mg/24 h, range 15–1161, p < 0.05). In addition, fewer patients in the captopril/diltiazem group progressed to macroalbuminuria (eight patients in captopril group and one in captopril/diltiazem group, p < 0.05). The beneficial effects of the addition of diltiazem were independent of blood pressure and metabolic control. We suggest that the combination of ACE inhibitors and NDCA should be considered in type 2 microalbuminuric patients at high risk for progression to established diabetic nephropathy.