Water pills may work as well as other commonly used high blood pressure pills to protect the hearts of people with type 2 diabetes.

The researchers say they found "no evidence" that newer, more costly high blood pressure medications were better at preventing heart disease deaths or heart attacks than water pills, also called diuretics.

The findings were complex and "must be interpreted with caution," they write in the Archives of Internal Medicine.

They say the type of diuretics they studied "should be strongly considered" as initial drug therapy for patients with high blood pressure and type 2 diabetes or prediabetes.

Read WebMD's "Glucose Meters: What's on the Horizon?"

About High Blood Pressure

Nearly one in three U.S. adults has high blood pressure. But almost a third of them don't know it, says the American Heart Association (AHA). High blood pressure affects nearly 50 million people in the U.S. and approximately 1 billion worldwide, according to the National Heart, Lung and Blood Institute (NHLBI).

Uncontrolled high blood pressure can be very dangerous. It can raise the risk of heart attack, stroke, heart failure, or kidney failure, says the AHA.

The relationship between blood pressure and heart disease risk is a continuous and consistent one, says the NHLBI. The higher the blood pressure, the greater the risk of heart attack, heart failure, stroke, and kidney disease. People with diabetes and high blood pressure have approximately twice the risk of complications compared with people who have high blood pressure alone.

Medications can help curb high blood pressure and reduce the risk of complications from the disease. A healthy lifestyle — including exercise and good nutrition — can also make a difference.

High Blood Pressure and Diabetes

"Almost three out of every four persons with type 2 diabetes has [high blood pressure]," says Paul Whelton, MD, MSc, in a news release.

That puts those people at "substantial risk" for heart disease, he says.

Whelton worked on the diuretic study. He is Tulane University's senior vice president for health sciences.

Read WebMD's "Diabetes Diagnosis Is Traumatic for Parent"

Study's Structure

Whelton's study included more than 31,500 adults aged 55 and older.

All had high blood pressure and at least one other heart disease risk factor. More than 13,000 had type 2 diabetes or an abnormal fasting blood sugar.

Patients were assigned to take one of three drugs initially:

— A diuretic called chlorthalidone

— An ACE inhibitor called lisinopril (Prinivil or Zestril)

— A calcium channel blocker called Norvasc

They were tracked for five years, on average. Most people with diabetes and high blood pressure require more than one drug to achieve a target blood pressure goal of less than 130/80.

Researchers' Results

Whelton's findings include:

—The ACE inhibitor and calcium channel blocker were not better than the diuretic in preventing heart disease death or nonfatal heart attacks.

— More stroke protection for black patients taking the diuretic than the ACE inhibitor, regardless of diabetes.

— Heart failure was less common in those taking the diuretic, with or without diabetes. The difference in heart failure with the ACE inhibitor was very small.

— Systolic blood pressure (the first number in a blood pressure reading when the heart beats) was lower with diabetes patients taking the diuretic. According to the NHLBI, if left uncontrolled, high systolic pressure can lead to stroke, heart attack, heart failure, kidney damage, blindness, or other conditions. Systolic blood pressure becomes more important as people get older.

— Diastolic blood pressure (the second or lower number of the blood pressure reading, when the heart rests in between beats) was lower in diabetes patients taking the calcium channel blocker. The diastolic blood pressure is especially important for younger people. The higher the diastolic blood pressure, the greater the risk for heart attacks, strokes, and kidney failure, writes the NHLBI.

Read WebMD's "Newly Diagnosed with Diabetes? Start Here"

More to Come

The researchers say they'll publish more details from the study in the future.

Meanwhile, they say the type of diuretics they studied are effective, have been tested in many trials, and are the least expensive prescription drugs for the condition.

An earlier report on the study appeared in The Journal of the American Medical Association in December 2002.

By Miranda Hitti, reviewed by Brunilda Nazario, MD

SOURCES: Whelton, P. Archives of Internal Medicine, June 27, 2005; vol 165: pp 1401-1409. American Heart Association: "High Blood Pressure." News release, Tulane University. WebMD Medical News: "Diuretics Best for High Blood Pressure." National Heart Lung and Blood Institute