Objective: To assess the relative effect of different antihypertensive agents on proteinuria and renal function in patients with diabetes.
Data Sources: We used MEDLINE and bibliographies in recent articles to identify studies of the effects of antihypertensive agents on renal function in patients with diabetes.
Study Selection: We selected 100 controlled and uncontrolled studies that provided data on renal function, proteinuria, or both, before and after treatment with an antihypertensive agent.
Data Extraction: Data on blood pressure, renal function, proteinuria, patient characteristics (for example, age, sex, and type of diabetes), and study design (for example, random allocation and the use of a placebo) were extracted from selected studies.
Data Synthesis: Multiple linear regression analysis indicated that angiotensin-converting enzyme (ACE) inhibitors decreased proteinuria independent of changes in blood pressure, treatment duration, and the type of diabetes or stage of nephropathy, as well as study design (P < 0.0001). Reductions in proteinuria from other antihypertensive agents could be entirely explained by changes in blood pressure. Blood pressure reduction in itself was associated with a relative increase in glomerular filtration rate (regression coefficient [±SE], 3.70 ±.92 mL/min for each reduction of 10 mm Hg in mean arterial pressure; P = 0.0002); however, compared with other agents, ACE inhibitors had an additional favorable effect on glomerular filtration rate that was independent of blood pressure changes (3.41 ± 1.71 mL/min; P = 0.05).
Conclusion: Angiotensin-converting enzyme inhibitors can decrease proteinuria and preserve glomerular filtration rate in patients with diabetes. These effects occur independent of changes in systemic blood pressure.