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Improvements in diabetes care fail to slow rise in diabetic kidney disease, UW study finds

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Despite marked improvements in diabetes care, kidney disease due to the complications of diabetes continues to rise, researchers from the University of Washington report.

Diabetic kidney disease is one of the leading causes of death among people with diabetes and is responsible for nearly half of the cases of end-stage renal disease cases in the U.S.

In the study, Dr. Ian de Boer, assistant professor of medicine at the UW’s Division of Nephrology, and colleagues compared rates of diabetes, diabetic kidney disease and the use of medications that have been shown to reduce the risk of several complications of diabetes from data collected between 1988-1994, 1999-2004, and 2005-2008.

During this time, physicians in the U.S. began to treat diabetes much more aggressively after a number of studies showed that tighter control of blood sugars, blood pressure and cholesterol reduced the risk that patients with diabetes would develop diabetic eye disease, heart attacks and strokes, as well as diabetic kidney disease, as measured by the amount of a blood protein in the urine, called albumin.

The presence of albumin in the urine, or albuminuria, is an early sign of kidney damage.

At the start of the study, Dr. De Boer said he expected that there would be an increase in the prevalence of diabetic kidney disease because over the past two decades there has been a marked increase in the prevalence of type 2 diabetes, driven by the growing numbers of Americans who are obese.

Dr. Ian de Boer

But, Dr. De Boer said, he had expected that improvements in blood sugar control, the use of a class of blood pressure medicines, called renin-angiotensin-aldosterone system (RAAS) inhibiters, and cholesterol-lowering treatments would at least slow the rise of diabetic kidney disease.

“They’re good medications; they’re proven to work, and they would all be expected to have some benefit on kidney disease,” he said in a phone interview.

Instead, Dr. De Boer and his colleagues found that over the past two decades the prevalence of diabetic kidney disease rose in parallel with the rise of diabetes, despite the fact that the use of blood sugar-lowering and RAAS-inhibitor treatments increased markedly.

One reason why the treatments did not have the expected effect on kidney disease was that early clinical trials testing these medicines relied on the level of albuminuria to assess kidney damage.

In the new study, the researchers looked at albuminuria as well as another test of kidney function called the glomerular filtration rate, or GFR.

This measure assesses the ability of the kidney’s ability to clear toxins, one the kidney’s key functions.

The researchers found that while there was some decrease in the prevalence of albuminuria over time, that drop was not statistically significant, meanwhile the prevalence of impaired GFR rose.

When those measures of kidney damage were taken together, the prevalence of diabetic kidney disease rose in parallel with the rise in the prevalence of diabetes overall, suggesting the more aggressive treatment of diabetes and its complications is failing to blunt the rise in diabetic kidney diseases, Dr. De Boer said.

The findings should not be taken to mean that current treatments do not prevent other complications of diabetes, Dr. De Boer cautioned, because there’s good evidence that they do reduce the risk of diabetic eye disease, nerve damage, heart disease and stroke.

And it’s possible these treatments are helping prevent diabetic kidney disease, he noted, but that it just taking longer for these treatments  to show their benefits.

However, the findings suggest that new treatments may need to be designed to prevent declines in GFR and not just albuminuria, he said.

The findings also underscore the point that the most effective approach to preventing diabetic kidney disease remains preventing the cause–diabetes–in the first place, Dr. De Boer said. “Prevention should be the focus — and that means focusing lifestyle, weight loss, diet and exercise.”

The study “Temporal Trends in the Prevalence of Diabetic Kidney Disease in the United States” appears in the current issue of JAMA, the Journal of the American Medical Association. Dr. De Boer is the lead author of the paper; Dr. Jonathan Himmelfarb is the paper’s senior author.

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