Kidney damage is a constant danger for people with diabetes, especially when their blood pressure is high. Dr. Kaspar Rossing of Steno Diabetes Center in Gentofte, Denmark, and colleagues note 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One patient developed dangerously lower potassium levels and had to be withdrawn from the study, but recovered rapidly.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 conclude that in the short term, spironolactone may offer beneficial renal and cardiovascular protection.

Source: Diabetes In Control.com: Diabetes Care, September 2005.