Men with cardiovascular disease may be at significantly increased risk for death even with a blood glucose level in the normal range, according to an article in the February 15 issue of the American Journal of Epidemiology.

In the current study, American researchers examined the statistical correlation between blood glucose level and death in men with known cardiovascular disease. Currently, doctors consider a glucose level of 100 or less to be normal, 101-126 to be impaired and above 126 to be diabetic.

The investigators used data from the Framingham Heart Study. The sophisticated statistical analysis made adjustments for factors such as cholesterol level, blood pressure, cigarette smoking, body mass index, and antihypertensive drug use.

The analysis included more than 686 men ages 45 to 74 years, who had been diagnosed with cardiovascular disease. Because researchers' statistical technique allowed them to take advantage of the fact that many patients were examined over multiple two-year periods, they reported on more than 3,800 observations.

"Our findings suggest that for men with cardiovascular disease, there is apparently no 'normal' blood sugar level," said Sidney Port, PhD, UCLA professor emeritus of mathematics and statistics, and lead author of the study. "For these men, across the normal range, the lower their blood sugar, the better. Their death rate over a two-year period soars from slightly more than 4 percent at a glucose level of 70 (mg/dL) to more than 12 percent at 100 (mg/dL) - an enormous increase."

Surprisingly, however, and contrary to conventional belief, above 100 (mg/dL), risk remained the same. The death rates at 100 and 150 were the same. Although these data suggest that blood glucose level for men with cardiovascular disease should be as low as possible, co-author Mark Goodarzi, assistant professor-in-residence at Cedars-Sinai Medical Center's Division of Endocrinology, cautioned that the study by no means proved that deliberately lowering glucose would reduce mortality.

"Such a fact can be established only by a suitable clinical trial" Goodarzi said.
Currently, no such trials are scheduled. The same research team is currently analyzing whether blood glucose levels are linked with death or development of cardiovascular disease in people who have not been diagnosed with cardiovascular disease.