New Clues To Protecting Diabetic Kidneys

Drugs that block the renin-angiotensin system (RAS blockers) may help protect people with diabetes from kidney damage by improving blood flow to the kidneys, according to two new studies. RAS blocker medications have long been successful in preventing kidney damage in diabetics, but the exact mechanisms behind that effect have remained unclear. In the first study, researchers at Medical School Hanover studied the impact of the RAS blocker olmesartan on blood flow patterns and kidney function in 19 diabetics. Another group of 19 diabetics received a placebo. Both groups were treated for 12 weeks. They found the drug reduced blood pressure and increased the rate of blood flow to the kidneys. This improvement in blood flow was accompanied by a reduction in renovascular resistance, a measurement of resistance to blood flow in the kidneys. Patients taking the placebo continued to have decreased blood flow to the kidneys and a slight increase in renovascular resistance, the researchers report. According to the study, diabetics taking olmesartan also displayed reduced signs of oxidative stress -- a buildup of unstable, potentially harmful molecules linked to cardiovascular disease. This lends support to recent research suggesting that oxidative stress may contribute to kidney damage in people with diabetes, the researchers said. A second study, this time from researchers in Japan, resulted in similar findings. Researchers at Kagawa Medical University studied the effects of RAS blockers in rats bred to develop diabetes as they mature. Some of the rats were given one or two types of RAS blockers, while other rats received the non-RAS-blocker drug hydralazine. The rats received the drugs while they were juveniles, before they developed diabetes. Treatment with the RAS blockers did not prevent the rats from developing diabetes at maturity. However, the rats that received the RAS blockers did display less diabetes-related kidney damage than the rats that received hydralazine. The findings suggest that early treatment with RAS blockers may help reduce long-term risk of kidney damage in people with diabetes. A study is underway to determine if treatment with the RAS blocker olmesartan can reduce kidney disease in people with diabetes. Both studies appeared in recent issues of the Journal of the American Society of Nephrology.

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