SUNDAY, Oct. 31, 2004 (HealthDayNews) -- Two new studies show that standard blood pressure medications may have an even greater effect than originally thought on kidney disease in people with type 2 diabetes.
One study found the early stages of kidney disease can be prevented altogether while the other found the progression of the disease could be halted.
Both reports appear in the Nov. 4 issue of the New England Journal of Medicine, but were released Oct. 31 to coincide with presentations at the American Society of Nephrology's annual meeting in St. Louis.
"This provides even more evidence that there's something we can do very positive for people who have diabetes and kidney disease," said Dr. William E. Mitch, author of an accompanying perspective article in the journal.
"It's no longer, 'There's nothing we can do for you,'" added Mitch, president of the American Society of Nephrology and a professor of medicine at the University of Texas Medical Branch in Galveston.
Type 2 diabetes is quickly becoming epidemic around the world and, with it, a secondary epidemic of kidney disease is taking hold. In the United States, type 2 diabetes is the leading cause of end-stage kidney disease and accounted for about 40 percent of patients who began dialysis between 1994 and 1999.
The numbers are only going to get higher as the number of people with type 2 diabetes is expected to jump worldwide from more than 170 million today to 370 million by 2030, experts predict.
"We're expecting an overwhelming number of people with diabetes and kidney disease," Mitch said. "The issue is what can we do to help these patients preserve their kidney function without any danger to themselves and, at the same time, try and prevent them from going to dialysis or transplantation."
One of the first signs of kidney disease is a condition known as microalbuminuria, or leakage of protein into the urine. Microalbuminuria is generally not reversible and, typically, will progress to more serious kidney problems. Right now, standard practice is to wait until a patient develops this condition before treating it, said Dr. Giuseppe Remuzzi, senior author of one of the studies and director of the Mario Negri Institute for Pharmacological Research in Bergamo, Italy.
To see if there might be a way to prevent microalbuminuria and the cascade of damage it heralds, Remuzzi and his colleagues randomly assigned 1,204 people to receive either an ACE inhibitor (trandolapril) plus a calcium channel blocker (verapamil), the ACE inhibitor alone, the calcium channel blocker alone or a placebo. The participants were followed for at least three years.
Microalbuminuria developed in 5.7 percent of the patients on the combination regimen, 6 percent of the participants on trandolapril alone, 11.9 percent of those receiving verapamil alone and 10 percent of the placebo group.
"Compared to placebo, ACE inhibitor either in combination with the calcium channel blocker or alone decreased the risk of developing microalbuminuria by about 50 percent whereas the other had no effect," Remuzzi said.
The message is don't wait for evidence of microalbuminuria to treat people with type 2 diabetes.
The second study was the first head-to-head, long-term comparison of two hypertension drugs used in people with early stages of diabetic kidney disease.
In this multi-country trial involving 250 people, telmisartan, an angiotensin II receptor blocker, turned out to be essentially equivalent to enalapril, an ACE inhibitor, at treating kidney disease. Both drugs work by inhibiting what's known as the angiotensin system, a hormone system.
"There was equivalence as far as kidney protection went but what was really exciting was that not one patient went into end-stage disease, not one needed dialysis and not one developed significant chronic renal failure during the five years of the study," said study author Dr. Anthony Barnett.
"We would have expected around one quarter to go into significant renal failure," said Barnett, a professor of medicine at the University of Birmingham in England.
The other surprising and welcome finding was that both drugs essentially froze the damage, preventing any further progression of the disease. Mortality rates were also low.
These drugs appear to have a protective effect on the kidneys over and above their effect on blood pressure.
"The argument has always been, is it blood pressure control or is it something else," said Dr. Stuart Weiss, clinical assistant professor of medicine at New York University School of Medicine. "The news is that it's not just blood pressure control, it's something else about these drugs that protected against the combination of high blood pressure and diabetes."
Barnett added: "An inhibitor of the angiotensin system, either an ARB (angiotensin II receptor blocker) or an ACE inhibitor, should normally be the first-line treatment in context. An inhibitor should be a normal part of clinical practice management in all type 2 diabetics with raised blood pressure. If you've got type 2 diabetes you should be on one of these drugs even if don't have protein leakage."
More information
For more on kidney disease and type 2 diabetes, visit the National Institutes of Health.
