Every diabetic is familiar with fasting blood glucose tests. You don't eat for at least eight hours, you check your blood sugar, and by that, you establish what your baseline glucose is.
This was at least the traditional idea of blood sugar testing. But given that most of us spend a lot of the day -- maybe even most of the day -- having eaten something within the last few hours, can we really call the glucose levels we have after eating "abnormal"? In fact, isn't it more abnormal to go eight hours during the day without eating or drinking anything?
When television's perennially popular Mary Richards walked into WJM's Minneapolis newsroom in 1970, she did more than show the world a single girl could "make it on her own." The award-winning actress who portrayed her -- Mary Tyler Moore -- also showed us diabetes and a career could coexist.
Moore was diagnosed with adult-onset type 1 diabetes in the 1960s, several years before her Emmy-winning show began. But that didn't stop Moore from pursuing her career or turning the world on with a smile...
In short, this is the idea behind postprandial -- or after-meal -- glucose testing. Since we spend so much time in a postprandial state, the argument goes, it's important to monitor bloodglucose levels during that time, too. While it may make intuitive sense, postprandial testing is one of the most hotly debated subjects in diabetes care. Is it an important new way of testing blood glucose that will reshape diabetes treatment, or is it merely a distraction from what's really important?
Setting the Limits
Paul Jellinger, MD, past president of the American Association of Clinical Endocrinologists (AACE), is a firm believer in the importance of postprandial testing. In 2001, when Jellinger was president of AACE, the organization issued a consensus paper on diabetes treatment that discussed postprandial testing.
"What we came up with was a number of new guidelines for postprandial testing," Jellinger tells WebMD. "We made a recommendation that a person's postprandial blood sugar, taken two hours after eating, should not exceed 140 mg/dL."
How did they arrive at that limit? Given the ways in which we all eat, postprandial testing would seem inherently imprecise; for instance, the glucose level of someone who just ate a salad for lunch might be pretty different from someone who just finished a Thanksgiving dinner. To resolve this issue, the AACE set a cutoff based on a comparison of the typical glucose levels of diabetic and non-diabetic people after eating.
"We know that in a normal person without diabetes, it's very rare for his or her blood sugar to exceed 140 mg/dL two hours after a meal," says Jellinger. "It can happen, but not often."
However, Jellinger is quick to concede that the cutoff number has been contentious. Just because people without diabetes don't usually reach a blood-glucose level of more than 140 mg/dL does not necessarily mean that anything above that particular number increases the risks of diabetic complications.
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