Men with cardiovascular disease may be at considerably increased risk for death even when their blood sugar level remains in the "normal" range, suggests a new study by a team of scientists at UCLA and Cedars-Sinai Medical Center in Los Angeles.
The study, a statistical analysis examining the connection between glucose (blood sugar) levels and death in patients with cardiovascular disease, is published in the American Journal of Epidemiology.
Cardiovascular disease includes coronary heart disease, stroke, angina and peripheral vascular 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.
"Our findings suggest that for men with cardiovascular disease, there is apparently no 'normal' blood sugar level," said Sidney Port, 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), their risk does not seem to change -- it stays at the same high level -- no matter how high above the normal range, Port said. Their death rate at 100 and 150 is the same. Although these data suggest that blood sugar 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, cautions that their study by no means proves 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.
In another surprising result that Port and his co-authors cannot explain, women with cardiovascular disease show a dramatically different response from men. "For women, we found no evidence of any change in risk across the normal range, from 70 to 100, but then their risk seems to rise quickly through the impaired range and continues to increase with higher glucose in the diabetic range; therefore a blood sugar level of 100 seems to be a sensible cut point for women with cardiovascular disease."