Effects of antihypertensive therapy on progression of diabetic nephropathy

There is a clear relationship between hypertension and the microvascular complications of diabetes. Genetic predisposition to hypertension has been correlated to the risk of diabetic nephropathy in type I diabetes, and hypertension is a well known risk factor for developing nephropathy in patients with type II diabetes. Multiple studies have emphasized the importance of hypertension on renal disease progression, and blood pressure control with conventional antihypertensive drugs slows the rate of renal function loss in diabetic nephropathy. Furthermore, evidence of the role of renin-angiotensin system (RAS) on progression of renal damage has focused much interest on the therapeutic action of the RAS blockade. In patients with type I diabetes, blocking the RAS with angiotensin converting enzyme (ACE) inhibitors prevents progression from microalbuminuria to overt nephropathy, and in overt nephropathy decreases the gradual loss of renal function beyond its blood pressure lowering effect. Less clinical information is available in type II diabetic nephropathy, but our experience and some recent studies suggest that ACE inhibitors also have a renoprotective action in type II diabetes. The role of calcium channel blockers in diabetic nephropathy is not clear. Several short-term studies with the first generation dihydropyridine calcium antagonists showed a lower effect on urinary albumin excretion and a more rapid progression to renal failure than with ACE inhibitors. However, other calcium channel blockers, particularly of the non-dihydropyridine type, have been shown to have a beneficial effect on diabetic nephropathy, decreasing proteinuria and slowing progression.