Written by Steven Reinberg

Updated on September 20, 2004

MONDAY, Sept. 20, 2004 (HealthDayNews) -- High blood sugar levels aren't a heart disease concern for diabetics only.

While it has been long known that diabetics have higher odds of heart disease and stroke when their blood sugar is not controlled, a new study suggests a high glucose mark is a risk factor in nondiabetics as well.

"Diabetes is well-recognized to be associated with increased risk of cardiovascular disease," said lead author Dr. Kay-Tee Khaw, a professor at the School of Clinical Medicine at the University of Cambridge in England.

However, even in people who do not have diabetes, levels of glycated hemoglobin, which is an indicator of long-term blood glucose level, predicted cardiovascular disease incidence and total mortality in 10,232 men and women aged 45 to 79 living in the general community in Britain, who were followed up over six years, she said.

The relationship of cardiovascular disease and mortality was continuous and increased with increasing blood glucose levels, even across the normal, nondiabetic range, in a linear relationship, Khaw said.

According to the report, an increase of glycated hemoglobin of 1 percent was associated with about a 25 percent higher risk of death. "Fifteen percent of the deaths occur in the 4 percent of the population with diabetes or glycated hemoglobin levels of 7 percent or more, but 72 percent occurred in those with glycated hemoglobin levels above the optimal level of less than 5 percent," she said.

The increased risk was independent of classical cardiovascular disease risk factors including age, blood pressure, blood lipids, cigarette smoking and body mass index, Khaw said.

The report appears in the Sept. 21 issue of the Annals of Internal Medicine.

"Even in persons without diabetes, higher levels of glycated hemoglobin may indicate persons at higher risk of cardiovascular disease," Khaw said. "This may be helpful in identifying those who may benefit most from preventive interventions, such as cholesterol-lowering or blood pressure- lowering medication."

Khaw said there is no evidence from intervention studies that lowering blood glucose levels in people who do not have diabetes may reduce heart disease.

"However, we already know from trials that behavioral interventions, such as physical activity and reduction of obesity, can reduce blood glucose levels and prevent diabetes in high-risk individuals. This may strengthen existing advice for lifestyle modification to prevent cardiovascular disease in the general population," she said.

In another report in the same journal, Elizabeth Selvin, a graduate student in the Department of Epidemiology at the Johns Hopkins Bloomberg School of Public Health and her colleagues add to the evidence of the connection between high blood sugar and heart disease among diabetics.

Selvin's team reviewed 13 previously published studies on the relationship between glycosylated hemoglobin and heart disease risk.

They found that people with type 2 diabetes had an 18 percent increased risk for cardiovascular disease for each 1 percent increase in glycosylated hemoglobin level. In addition, people with type 1 diabetes had a 15 percent increase risk for cardiovascular disease risk for each 1 percent increase in glycosylated hemoglobin level.

"In persons with diabetes, it is clear that known risk factors for cardiovascular disease such as high blood pressure, high cholesterol and smoking should be treated aggressively," Selvin said. "But our study suggests that patients and physicians should also be paying attention to blood sugar levels to prevent heart disease in persons with diabetes. Our results suggest that lowering glucose levels in persons with diabetes may further reduce their risk of heart disease."

"It is clear from the two articles that an abnormal glucose level is now well-established as a risk factor for future heart attacks and strokes and deaths from cardiovascular disease," said Hertzel Gerstein, a professor of medicine at McMaster University in Canada.

Gerstein, the author of an accompanying editorial, said glucose levels should be considered in the same way as cholesterol levels or blood pressure. "It's a marker for cardiovascular risk in everybody, not just in people with diabetes," he added.

To combat high glucose, Gerstein recommends moderate physical activity and eating less. "We know that if everybody were able to make these minor changes, they would reduce their risk of diabetes and rises in glucose levels," he said.

More information

Learn about risk factors for heart disease from the American Heart Association.

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