ANAHEIM, Calif. (AP) _ A blood fat measurement widely ignored by doctors could be an important predictor of heart disease and diabetes in patients with high cholesterol, researchers said Sunday.

The fats, called triglycerides, have been widely thought to have little effect on heart disease risk unless they occurred at far higher than normal levels in the blood, said Dr. Antonio Gotto of the Baylor College of Medicine in Houston.

Studies presented Sunday in conjunction with the American Heart Association's annual meeting suggest that even mildly elevated triglyceride levels may be an important indicator of heart disease risk, Gotto said.

Last year, a survey of doctors found that only 7 percent thought triglycerides were useful in evaluating heart disease risk, Gotto said.

That should change, Gotto said. ''Physicians should take into account triglyceride levels'' when trying to determine how to reduce a patient's risk of heart disease, he said.

Triglycerides appear to be especially important in patients with high levels of the so-called bad form of cholesterol, the low-density lipoproteins, or LDLs, Gotto said.

''For a given level of LDL, if a patient also has high triglycerides, they're at higher risk,'' he said.

Dr. William Castelli reached a similar conclusion in an analysis of data from the Framingham Heart Study, an influential study of heart disease in the people of Framingham, Mass., a small city west of Boston.

People with high triglycerides were at significantly increased risk of heart disease, he said.

Castelli also reported that people with high triglyceride levels have the highest blood sugar levels and have twice the risk of developing diabetes as do people with normal triglyceride levels.

Dr. Basil Rifkind of the National Heart, Lung and Blood Institute in Bethesda, Md., said the institute had not yet changed its recommendations on the interpretation of triglyceride levels. But a conference to consider the issue has been called for February, he said.

''The question is, 'Should eveyone know their triglyceride levels?' And what do we do if we find them high?'' he said.

He acknowledged that many researchers, including Gotto, believe that triglycerides should be considered in the prevention and treatment of heart disease. But he said, ''others don't think we have everything we need to make this part of a national program.''

Triglycerides are the saturated and unsaturated fats that people consume in their diets. Triglycerides are also made in the body.

Blood triglyceride levels can be lowered with a low-fat diet and with drugs, Gotto said.

Doctors have believed that a blood triglyceride measurement above 500 was abnormal, and that levels between 250 and 500 were in an intermediate range, possibly requiring treatment.

The new evidence suggests that anyone with a triglyceride level above 200 should be considered for treatment, Gotto said.

Several other researchers reported that people with high triglyceride levels have a different kind of low-density lipoprotein that increases the likelihood of blockage of the arteries.