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Glucose Testing: After Meals?

Should diabetics test their blood sugars after eating, too? The debate continues.

The Proponents

"I think postprandial testing is very important," says Om Ganda, MD, director of the lipid clinic at the Joslin Diabetes Center and associate clinical professor at Harvard Medical School. "In order to control diabetes well, you need to control the blood sugars 24 hours a day, and not just when you're fasting. People can have a pretty normal fasting blood sugar but still have a high postprandial level."

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 tests.

"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."

The Problems

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.

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