Los Angeles - It seemed like a good idea. Diabetics are at an unusually high risk of heart disease, heart attacks and strokes, so treating them intensively to sharply reduce blood pressure, cholesterol and blood sugars should be highly beneficial. But a decade of studies in thousands of patients shows that is not the case.

Two new reports from a major nationwide trial called ACCORD released yesterday show that lowering either blood pressure or cholesterol below current guidelines does not provide additional benefit and, in fact, increases the risk of side effects. A third arm of the study, released two years ago, showed that lowering blood sugars excessively actually increases the risk of heart disease.

The results are disappointing, researchers say, because they suggest that clinicians might have reached the limit of what they can do for diabetic patients.

The good news is that the findings "reduce the cost and potential side effects of drug therapy," and patients will not have to work as hard at reducing blood sugars, lipids and blood pressure, said Dr. Denise Simons-Morton of the National Heart, Lung and Blood Institute, which funded the trial.

Diabetes has become a tremendous problem in the United States: At least 21 million people are afflicted with Type 2 diabetes, and millions more are at risk because of obesity. Most diabetics also have high blood pressure and a high cholesterol level; those factors raise their risk of heart attack and stroke to the same level as that of people who have had a heart attack.

Many doctors have reasoned that aggressively lowering blood pressure and lipids below nationally recommended levels might decrease the risk of heart disease, and ACCORD was created to study that.

In one arm of the study, Dr. William C. Cushman of the Veterans Affairs Medical Center in Memphis and his colleagues at 77 medical centers enrolled 4,733 diabetics with high cholesterol and existing cardiovascular disease or a high risk of developing it. They were randomly assigned to treatment regimens to lower their systolic blood pressure - the top number in a blood pressure measurement - below either 140 or 120.

Cushman reported yesterday at an Atlanta meeting of the American College of Cardiology and in a paper published online in The New England Journal of Medicine that the treatment group achieved an average systolic blood pressure of 119 but had no decrease in heart attacks, cardiovascular disease or deaths.

In the second arm of the study, 5,518 similar patients with high cholesterol were split. One group was given the cholesterol-lowering drug simvastatin; the other was given both simvastatin and fibrate, another class of cholesterol-lowering drugs. The addition of fibrate provided no benefit on any measure.