Will A Glucose Tolerance Test Be Affected By A Low-carb Diet?
I have to get a glucose tolerance test. However, I haven’t been eating very much for a while and have cut out all sugar and most carbs……….I’m worried this is going to make my glucose tolerance results appear lower than they actually are.
Should I eat normally for a couple days and then go get the test?
A Glucose Tolerance Test starts from a position of overnight fasting, thereby giving your natural, low blood sugar as a baseline. They need to see it as it is. Your fasting blood sugar is first of all tested. If you are considered safe to proceed, (i.e: not hyperglycaemic) you then drink a measured beaker of glucose dissolved in water and blood sugars are measured at half hourly intervals to see how it rises, stabilises and falls. After about 2.5 or 3 hours it should be back to the pre-start level, showing your body’s insulin has kicked in (non-diabetic status). If it is too high (hyperglycaemic), then there is a problem. So try to eat as you intend to go on. If the pancreas is not producing adequate, good quality insulin, or there is a shortage of insulin receptor cells then diagnosis and treatment are called for. If you totally avoid carbs you will start burning fat, then protein which puts you at risk of ketoacidosis, a very much more dangerous condition than well managed diabetes.
No.
Eating correctly will make your blood sugar levels drop closer to normal, but it will NOT affect the Glucose Tolerance Test.
The Glucose Tolerance test is an “instantaneous” measurement of how well your body handles sudden intakes of sugar.
Simply put:
You need to fast before the test. The doctor will take a blood sugar reading to establish a baseline. Next, you will have to drink a really sweet liquid (liquid glucose). The doctor will then take many blood sugar measurements over the next 2 to 4 hours to determine how fast your body handles that sugar.
This test will show IF you are diabetic. if your body handles the sugar quickly (in like 90 minutes) then you are not diabetic. if your body handles the sugar slowly, or not at all, then you are diabetic.
IF you show diabetes, the doctor may give you an insulin shot to bring your blood sugar back down to normal.
Since you have been requested to take the test, it is a good idea for you to continue to eliminate sugars and reduced carbs, as the doctor thinks that you could easily become diabetic.
ALSO: ASK the doctor to perform an A1C test. if you are not diabetic, repeat this test every 6 months. if you ARE diabetic, repeat this test every 3 months, as a measure to see how well you are doing.
It will make your baseline fasting reading lower than it normally is. It would probably be a good idea to eat like you used to normally eat, so that the test will reflect normal conditions. Then after you are done the tests, you can go back to low carbing.
I had a test give a false negative because of this, so I’d eat normally for a while first. You certainly shouldn’t go hungry, that will definately skew the results.
Ask for an HbA1c test too, it is NOT affected fasting at all, and a day or two of low carbing won’t influence it that much because it reflects your blood sugars over the last 3 months. It does lean heavily towards the last two weeks though.
I’d get tested, then start making these dietary changes. You don’t want a misdiagnosis like I had. It just delays your treatment, and that’s dangerous.
hmmm i would think that your body would be more sensitive to the glucose due to your diet. this would probably cause a sharp spike in your sugars initially, but as long as your pancreas is going its job and producing insulin, your sugars should return back to normal in 2-3 hours. so over all your results should be fine. you might have a slightly different curve charting your sugar levels, but hey, everyone is different!!!
mention it to the doc/nurse doing the test and they might be able to answer in more depth!!!
if you are comfortable the way you are eating and you plan to stick to it in the long term then you should carry on. (as long as its a healthy balanced diet)
good luck!