Preventing Diabetes-Related Kidney Disease

Nov. 3, 2004 -- Combining two commonly prescribed blood pressure medications or taking a routinely prescribed blood pressure pill may help people with type 2 diabetes avoid kidney disease, according to a new study.

The commonly prescribed medications are an ACE (angiotensin-converting enzyme) inhibitor called Mavik and a calcium channel blocker called verapamil (also called Calan SR and Isoptin SR).

The study, which appears in the Nov. 4 issue of The New England Journal of Medicine, shows that these medications, when taken together, can help prevent kidney problems in people who have type 2 diabetes and high blood pressure. It shows that in people with type 2 diabetes and high blood pressure, the combination of an ACE inhibitor and calcium channel blocker reduced the risk of developing the abnormal presence of protein in the urine, which often foreshadows kidney failure.

The study also shows that protection from abnormal spillage of protein in urine, called microalbuminuria, occurred when an ACE inhibitor is used alone. However, protection against the development of microalbuminuria was not seen when people with type 2 diabetes and high blood pressure took the calcium channel blocker alone.

Type 2 diabetes is America's leading cause of end-stage kidney disease, and the global incidence of kidney disease among people with type 2 diabetes is expected to double by 2010, according to William Mitch, MD, of the University of Texas Medical Branch in Galveston, in an editorial in The New England Journal of Medicine.

Microalbuminaria may also foretell fatal heart problems, since 40%-50% of people with type 2 diabetes who have microalbuminaria eventually die of cardiovascular disease.

In the new study, researchers including Piero Ruggenenti, MD, of the Clinical Research Center for Rare Diseases in Bergamo, Italy, wanted to see if ACE inhibitors and calcium channel blockers helped.

Nearly 1,200 people participated in the study. All had type 2 diabetes and high blood pressure, but did not have microalbuminaria at the start of the three-year study.

Participants were randomly assigned to one of four programs: taking verapamil alone, taking Mavik alone, taking both drugs together, or taking a placebo. Their blood pressure and urine albumin (protein) levels were regularly monitored.

The drug combination group fared best, with 5.7% developing persistent microalbuminaria, compared with 6% of the Mavik group. However almost double (12%) the number of people with type 2 diabetes taking verapamil, and 10% of the placebo group developed microalbuminuria. Serious side effects were similar among the treatment groups.

In a second five-year study published in The New England Journal of Medicine, researcher Anthony Barnett, MD, of England's University of Birmingham, found that another drug, Micardis, which is an ARB (angiotensin II receptor blocker), performed as well as the ACE inhibitor Vasotec at protecting people with type 2 diabetes against a more advanced, yet still early form, of kidney dysfunction.

ARBs are similar blood pressure medications to ACE inhibitors, yet rather than blocking the formation of hormones, which can increase blood pressure, they block receptors where the hormones work to cause vessel constriction.

However, patients will need to do more than take pills, says Mitch. They should have their blood pressure, albumin, and glucose monitored, lose extra weight, exercise regularly, and, if blood pressure is a problem, limit dietary salt and possibly use a diuretic, he writes.