Drug protects kidneys of people with diabetes

NEW YORK (Reuters Health) – Kidney damage is a constant
danger for people with diabetes, especially when their blood
pressure is high. Now European researchers report that the
addition of a drug, spironolactone, to standard blood
pressure-lowering therapy for such patients helps reduce both
blood pressure and the amount of albumin protein in urine, a
measure of kidney impairment.

Dr. Kaspar Rossing of Steno Diabetes Center in Gentofte,
Denmark, and colleagues note in the medical journal Diabetes
Care that two types of antihypertensive drugs — ACE inhibitors
and angiotensin receptor blockers (ARBs) — have protective
effects on the kidneys in diabetics who already have kidney
damage.

These drugs work by controlling the release of a hormone
called aldosterone. While they’re effective initially,
aldosterone levels may subsequently rise once more in almost 40
percent of patients, resulting in greater urinary protein
levels and a faster decline in kidney function.

To see whether supplementary treatment with spironolactone,
which is an aldosterone inhibitor, might be helpful in these
circumstances, the researchers conducted a study with 21
patients with type 2 diabetes.

While the participants continued on their recommended
antihypertensive treatments (which included diuretics, ACE
inhibitors and ARBs), they were randomly assigned to take in
addition either an inactive placebo or spironolactone for 8
weeks. They then switched to the other pill for another 8
weeks.

During spironolactone treatment, urinary albumin levels
fell by 33 percent, and their upper and lower blood pressure
readings fell by 6 and 4 points.

One patient developed dangerously lower potassium levels
and had to be withdrawn from the study, but recovered rapidly.
Otherwise, the treatment was well tolerated.

The researchers call for further studies, but conclude that
in the short term, spironolactone may offer beneficial renal
and cardiovascular protection.

SOURCE: Diabetes Care, September 2005.