People with diabetes are known to be at greater risk than non-diabetics of suffering "restenosis," or a re-narrowing of an artery after an angioplasty or stent procedure. Yet there's been little research into the role blood sugar plays in that, the study's authors report.

"No one has really looked at outcomes after angioplasty," says study author Dr. Roberto A. Corpus, an interventional cardiology fellow at Mid America Heart Institute in Kansas City, Mo. The findings appear in the Jan. 7 issue of the Journal of the American College of Cardiology.

He hopes the study will provide an impetus for physicians to better manage blood sugar in their diabetic patients.

About 16 million people in the United States and 176 million people worldwide suffer from diabetes, a disease in which the body does not produce or properly use insulin, resulting in elevated blood sugar levels. Of the estimated 1.5 million revascularization procedures performed globally each year, a quarter involve diabetic patients, the study authors note.

In an editorial in the same journal, Drs. Ran Kornowski and Shmuel Fuchs of Rabin Medical Center in Petach-Tikva, Israel, state that 30 percent to 40 percent of patients who experience re-clogging of the arteries are diabetics. Reducing that rate would have a favorable impact on angioplasty and stenting results, they say.

The study at William Beaumont Hospital in Royal Oak, Mich., involved 239 patients having balloon angioplasty or stenting to open clogged arteries, including 179 people with type 2 diabetes. Sixty non-diabetic patients were randomly selected as a control group.

Each patient's hemoglobin A1c, a test that measures average blood sugar levels over the past two to three months, was taken before catheterization. The study used the American Diabetes Association's definition of optimal blood sugar control -- an A1c of 7 percent or less.

Diabetic patients with strict blood sugar control had a significantly lower rate of repeat procedures within a year of the initial angioplasty or stenting, compared with diabetics whose blood sugar levels exceeded 7 percent. Just 15 percent of patients with optimal blood sugar control required revascularization, compared to 34 percent of the group with suboptimal A1c levels.

The well-controlled group also had lower rates of recurrent angina and cardiac-related rehospitalizations at the 12-month follow-up.

Diabetics should be better managed, agrees Dr. Om Ganda, an associate clinical professor of medicine at Harvard Medical School and director of the lipid clinic at the Joslin Diabetes Center in Boston. But he questions the study's methodology, noting several "serious limitations," such as the failure to record follow-up blood sugar levels and the absence of data describing how long patients in the poorly controlled group had suffered from diabetes.

"Even though the conclusions are valid, they are not based on a good scientific study," Ganda says.