Glucose Testing: After Meals?
Should diabetics test their blood sugars after eating, too? The debate continues.
The Proponents continued...
While there haven't been a great number of studies of
postprandial hyperglycemia, there have been a number of suggestive studies of
something called post-challenge hyperglycemia. Post-challenge glucose tests are
administered after a person takes a set amount of glucose, usually 75 mg in a
liquid form. The precise relationship between post-challenge hyperglycemia and
postprandial hyperglycemia has not been firmly established, but proponents cite
a few studies that indicate a good correlation.
"There's a lot of epidemiological evidence coming from all
over the world suggesting that post-challenge blood sugars and thus
postprandial blood sugars have their own independent risks or at least greatly
augment understood risks," says Jellinger. "We thought that it was in
our patients' best interest to bring this issue to light."
Experts have been focusing an increasing amount of attention on
the cardiovascular risks of diabetes -- such as heart attack and stroke -- and
some epidemiological studies have suggested that postprandial hyperglycemia is
directly related to cardiovascular complications.
In addition, some suggest that postprandial testing may detect
people with impaired glucose tolerance (IGT) or impaired fasting glucose (IFG)
-- so-called "pre-diabetes" -- who might be missed by fasting
"Epidemiological evidence suggests that there are a lot of
people out there who don't have diabetes and who don't have pre-diabetes but
have abnormal postprandial glucose levels," Ganda tells WebMD. "And
based on a number of studies in the U.S. and Europe, they may be at an
increased risk of cardiovascular disease."
However, not everyone agrees that postprandial testing is so
important. No one debates that people with diabetes are more likely to have
postprandial glucose spikes -- or excursions -- than those without diabetes.
What is debated, and debated fiercely, is whether these spikes require any
specific treatment separate from typical care for diabetes.
"I think that the recent attention to postprandial glycemia
is a distraction," says David M. Nathan, MD, director of the diabetes
center at Massachusetts General Hospital and a professor of medicine at Harvard
Medical School. "In general, postprandial glycemia, fasting glycemia, and
chronic glycemia, as measured by the A1c test are highly correlated. Attention
should just be focused on overall lower glycemia."
Nathan points to the biggest problem with the postprandial
hyperglycemia hypothesis. While epidemiological research has suggested a
connection between postprandial hyperglycemia and diabetic complications, this
sort of research looks at a large number of variables and isn't designed to
test postprandial hyperglycemia specifically. There isn't yet a method to
single out the particular effects of postprandial hyperglycemia from other
common risk factors like hyperglycemia, obesity, and hypertension. As a result,
there's no way to know if postprandial glucose levels really matter on their
"I just don't think postprandial testing is worth putting
energy into now, because if you look for other risk factors of diabetes, you
will find all of these people anyway," says David E. Goldstein, MD,
principal investigator from the health sciences center at the University of
Missouri School of Medicine. "There just isn't evidence that postprandial
glucose levels matter independent of other factors, like A1c."
"But it's a hot topic now, though," Goldstein says
wearily. "It's a snake pit, or a bottomless pit. I don't know what to call