February 19 (HealthDay News) -- A combination of two blood pressure-lowering drugs reduced the risk of kidney disease by about 20 percent in people with type 2 diabetes, according to researchers who analyzed data from a study that included more than 11,000 patients.

The patients were randomly selected to receive either placebos or a combination of the angiotensin-converting enzyme (ACE) inhibitor perindopril and the diuretic indapamide. Most of the patients had high blood pressure, but 20 percent had normal blood pressure -- less than 130/80 mm Hg.

After an average follow-up of four years, patients taking the blood pressure-lowering drugs were 21 percent less likely to have kidney disease than those in the placebo group. The researchers also found that kidney function returned to normal among some patients who had early signs of diabetes-related kidney disease before they started taking the drugs.

Even in patients who didn't have high blood pressure, the drug combination reduced the risk of kidney disease.

More research is needed, but these results suggest that patients with type 2 diabetes might be considered for antihypertensive treatment even if they have normal blood pressure, said the authors of the study, which appears in the April issue of the Journal of the American Society of Nephrology.

The researchers noted their study did have important limitations, including the fact that it was an analysis of a previous clinical trail.

"Most of the findings related to early manifestation of kidney disease [albuminuria], and the study was not large enough to assess the impact of the intervention directly on the risk of kidney failure. We could not separate out the impact of the blood pressure-lowering combination used, or prove whether it had any effects beyond its blood pressure-lowering effects," study co-author Vlado Perkovic, of the George Institute for International Health in Sydney, Australia, added in an American Society of Nephrology news release.

SOURCE: American Society of Nephrology, news release, Feb. 18, 2009