Men with cardiovascular disease may be at considerably increased risk for
death even when their blood sugar level remains in the "normal" range.

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 2-year period soars from slightly more than 4% at a
glucose level of 70 mg/dL to more than 12% 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."

"Why there should be such a profound difference between men and women with
respect to how glucose affects mortality in the presence of atherosclerosis
is a mystery that needs to be further pursued," Goodarzi said. "To date, we
and colleagues we have consulted can offer no explanation."

"These large gender differences may have previously remained undetected
because earlier studies looked either at men and women together or a
younger, healthier group of men," said Port, whose study analyzed men and
women with cardiovascular disease separately. "If you look at men and women
combined, you get a highly distorted picture because they respond so
differently."

Using extensive heart study data from the town of Framingham, Mass.,
collected every second year since 1948, Port and his co-authors performed a
sophisticated statistical analysis, which made adjustments for factors such
as the patients' cholesterol levels, blood pressure, cigarette smoking, body
mass index and antihypertensive drug use. The researchers analyzed more than
1,200 people (686 men and 517 women), ages 45 to 74, diagnosed with
cardiovascular disease. Because the researchers' statistical technique
allowed them to take advantage of the fact that many patients were examined
over multiple two-year periods, they report on more than 3,800 observations.

In a follow-up study, they are analyzing whether blood sugar levels are
linked with death or development of cardiovascular disease in people who
have not been diagnosed with cardiovascular disease.

American Journal of Epidemiology. Feb 15th

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