July 2005 - In people with diabetes, diuretics work as well as ACE-inhibitors and calcium channel blockers in protecting against heart attack and improving survival, and offer more protection against congestive heart failure.
The latest findings from the "Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial" or ALLHAT, sponsored by the National Heart, Lung, and Blood Institute, were published in the June 27 issue of Archives of Internal Medicine.
ALLHAT is the largest study to compare these three major classes of medications to treat high blood pressure. The study originally reported in 2002 that diuretics were more beneficial as initial treatment for high blood pressure for protecting against adverse cardiovascular outcomes. This latest analysis shows that even among diabetics and those with mildly elevated fasting glucose--a sign of pre-diabetes--the less costly diuretics are at least as effective, may be more beneficial for some people.
About 73 percent of adults with diabetes have high blood pressure--which in diabetic patients is defined as greater than or equal to 130/80 mm Hg-- or use prescription medications for their hypertension. Both diabetes and high blood pressure are major risk factors for coronary heart disease, and when both are present, significantly increase the risk for developing heart and kidney diseases. High blood pressure can lead to congestive heart failure, a condition in which the heart is weakened and cannot pump enough blood throughout the body.
"Controlling high blood pressure is an urgent concern especially for people with diabetes. Our findings demonstrate the advantages of diuretics in diabetics as well as in those with impaired and normal fasting glucose levels," said NHLBI director Dr. Elizabeth G. Nabel. "As a physician, I have seen the consequences of poorly controlled hypertension and diabetes. These results show many people and their families can be spared that devastation."
The ALLHAT blood pressure study was a randomized, double-blind trial involving 42,418 participants with high blood pressure, ages 55 and older. Of those, 31,512 participants were randomly assigned to a diuretic (chlorthalidone); a calcium channel blocker (amlodipine); an angiotensin converting enzyme (ACE) inhibitor (lisinopril). 13,101 had diabetes, 1,399 had elevated fasting glucose and 17,012 had normal glucose levels.
Compared with the ACE inhibitor and the calcium channel blocker, the diuretic was:
- More protective against congestive heart failure in patients both with and without diabetes (by about 1/6 compared with the ACE-inhibitor, and by about 1/3 compared with the calcium channel blocker).
- More effective in lowering systolic blood pressure--the measure of blood pressure when the heart beats--among those with and without diabetes.
- At least equally protective against fatal coronary heart disease or non-fatal heart attacks in people with diabetes, those with elevated fasting glucose, and non-diabetics.
- Equally protective against death from all causes, end-stage kidney disease, or cancer in people with diabetes, those with elevated fasting glucose, and non-diabetics.
- In Black study participants, more protective against stroke in people with and without diabetes (compared with the ACE-inhibitor).
"This study shows the advantage of diuretics for preventing congestive heart failure in most people with high blood pressure-- regardless of diabetes status. Because some patients may respond differently to medications, they should discuss these results and their treatment with their doctors before making any changes", advises Dr. Jeffrey Cutler, NHLBI Senior Adviser.
There were more heart attacks among participants with impaired fasting glucose taking the calcium channel blocker compared with those taking the diuretic. This finding was unexpected and inconsistent with other results and may have occurred just by chance, according to Cutler.
Previous studies have found that ACE inhibitors slow progression of kidney damage in diabetic patients with kidney disease, who generally have protein in their urine. ALLHAT did not collect urine samples to measure protein (albumin) levels so analyses as to whether the ACE inhibitor was superior to the diuretic in this respect is not possible. However, an ALLHAT report in the April 25 Archives of Internal Medicine found no difference among the treatments in progression of kidney disease among diabetic patients with reduced kidney function.