Diabetics who strictly control their blood sugar levels also reduce their risk of heart attack and cardiovascular disease, British researchers report.

There have been several conflicting reports about the value of dramatically reducing blood sugar levels in diabetic patients in preventing heart attack and heart disease. In fact, some have suggested that significantly lower blood sugar levels could possibly be harmful.

"We show that if you lower glucose measures by something called HbA1c by 0.9 percent over five years, you reduce heart attacks by 17 percent," said lead researcher Dr. Kausik Ray, a senior clinical research associate from the University of Cambridge. "There is no excess risk of death in contrast to earlier claims."

The implications are enormous, Ray said. "There have been claims by doctors that lowering glucose to less than 7 percent could be harmful. We disprove that in the largest study to date," he said.

On average, diabetics die seven years earlier, and they need multiple interventions such as lowering blood pressure and cholesterol to reduce their risk of dying. "Despite this, the risk remains high, so better control of sugars further reduces residual risk," Ray said.

The report is in the May 23 issue of The Lancet.

For the study, Ray's team analyzed data from five studies that included 33,040 patients. Among all these patients, there were 1,497 heart attacks, 2,318 cases of coronary heart disease, 1,127 strokes and 2,892 people died.

The researchers noted hemoglobin A1c concentrations, or HbA1c, in the patients. More intensive blood sugar control was achieved when patients used additional medications and/or higher doses to get lower HbA1c levels.

HbA1c indicates average blood sugar concentration for the preceding two to three months. In general, healthy people who do not have diabetes have HbA1c levels ranging from 4 percent to 5.9 percent, while patients with diabetes usually have HbA1c levels over 6.5 percent, the researchers noted.