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Postprandial blood sugar is a measurement of how much glucose is in the blood after eating. Most people experience a rise in blood sugar after a meal, with the levels gradually returning to normal as the body processes the food. Consistently elevated blood sugar is a sign of diabetes or another health problem, and patients with abnormal results on a postprandial blood sugar test usually need more evaluation and screening to find out why and to develop an appropriate treatment plan.
If this test is recommended for a patient, he will be advised to eat two hours before the test is scheduled, and usually to eat a normal meal, to get an accurate reading on the patient's daily fluctuations in blood sugar. Sometimes, patients test their blood sugar at home to get the timing just right. In other cases, they report to a hospital or clinic for a blood draw, making sure they get the test on time so the results will be accurate.
In a one hour postprandial blood sugar test, levels are measured an hour after eating, when they should be elevated. Within two hours, they should have dropped to a normal range, below 140 milligrams per decaliter. If the levels are higher, the patient may have diabetes, and additional testing is needed. Blood sugar testing at other times of the day may be used to collect more information, including fasting blood sugar, which is usually taken first thing in the morning before the patient has breakfast, as well as a random glucose test.
Having elevated results on a postprandial blood sugar test doesn't automatically mean a patient has diabetes, although it is a warning sign. More testing is needed, including a repeat of the test in case there was a problem, as doctors want to avoid costly false positives. It may be possible for patients to get their blood glucose under control to prevent the development of diabetes if they are given early warning with postprandial blood sugar results, while other patients may need to enter diabetes treatment after testing reveals that they have this disease.
It can take between one and two hours to get the results of this test, depending on the lab. Patients who are concerned about their results can request an estimate on the length of time required and can also ask that they be contacted even if the results are normal. Sometimes, doctor's offices neglect to call patients with negative test results or assume the results can be delivered at the next appointment, and this can cause stress for worried patients.
When I was pregnant, I declined to take the glucose challenge test. (They usually have you drink a sugary drink and then check your blood sugar an hour later.) It seemed like a very artificial test, and it seemed silly to dump a bunch of sugar in my system when the rest of the time, I try so hard to avoid it!
I was offered an alternative: to do one fasting blood draw (before breakfast in the morning) and one postprandial. A diabetic would have his or her own checking equipment at home, but since I didn't, I had to go into the doctor's office. Both tests showed normal blood sugar levels, so I did not have to have any further testing for gestational diabetes. (They still dip your urine at every visit to make sure that you are not "spilling" sugar.)