Glucose tolerance test pregnancy
Glucose tolerance testing during pregnancy
Gestational diabetes screening tests and glucose tolerance tests are among the tests that may be offered to you during your pregnancy. These tests assess your body's response to glucose. They also provide your healthcare professional with important information to determine whether you have gestational diabetes or may be at risk. In the following article, we'll walk you through these different blood tests and what they mean.
What are gestational diabetes screening and glucose tolerance tests?
Gestational diabetes screening and glucose tolerance tests are done as part of your prenatal visits and help your healthcare provider determine how well your body processes glucose (sugar). The diabetes screening test helps determine if you may develop gestational diabetes, and the glucose tolerance test (or oral glucose tolerance test, OGTT) helps determine if you actually have the condition.
Gestational diabetes is a type of diabetes that can affect some pregnant women. It occurs when too much glucose remains in the blood instead of being used for energy. Gestational diabetes goes away after delivery.
What week is the gestational diabetes screening test done?
Some practitioners recommend that all pregnant patients, even those at low risk of developing diabetes, be tested for gestational diabetes between 24 and 28 weeks of pregnancy . However, other practitioners may not routinely offer it to pregnant patients younger than 25 years of age, who are less likely to develop gestational diabetes.
If you have one or more risk factors for developing gestational diabetes, your healthcare professional will likely suggest that you have a gestational diabetes screening test or glucose tolerance test at one of your earliest pregnancy visits, instead of waiting for the usual second-trimester screening.
If the gestational diabetes screening test indicates that you have high blood sugar (glycemia), your healthcare provider may perform a pregnancy glucose tolerance test. This second test will help determine more accurately whether you have gestational diabetes.
If you are considered to be at high risk for gestational diabetes, screening will be done fairly early in your pregnancy and, if the results are average, will probably be done a second time between weeks 24 and 28 to check that everything is still going well.
In summary
A woman at low risk for gestational diabetes will be tested between weeks 24 and 28 of pregnancy. A woman at higher risk may be offered testing before this date. If your results are higher than average, your provider will offer you a glucose tolerance test to determine if you do have gestational diabetes.
What are the risk factors associated with gestational diabetes?
For every pregnant woman, a urine sugar test is scheduled during the first prenatal visit. This gives an initial indication of your risk of developing diabetes during your pregnancy. In addition, your healthcare professional will be interested in the following known risk factors:
- Having already developed gestational diabetes during a previous pregnancy,
- Have a family history of diabetes,
- Suffer from obesity or overweight,
- Be over 35 years old,
- Have already given birth to a baby weighing more than 4 kg at term,
- Having certain illnesses, such as metabolic syndrome or polycystic ovarian syndrome (PCOS).
If your healthcare professional determines after the gestational diabetes screening test that you are not at particular risk, it may not be necessary to perform a glucose tolerance test during pregnancy.
In summary
Your healthcare provider will use the results of a urine test at one of your first prenatal visits to determine if you are at risk for gestational diabetes. They will also consider other factors such as your pre-pregnancy weight, your age, and your family and medical history.
What is the procedure for gestational diabetes testing and glucose tolerance testing?
As mentioned earlier, the first test is the gestational diabetes screening, a blood test that measures the amount of sugar in your blood. If these results are considered high, you will be offered a second test, the glucose tolerance test.
Gestational Diabetes Screening Test
The common screening test, sometimes called a glucose simulation test, involves having you drink a sugary syrup at the hospital or in a lab. A blood test is taken an hour later to determine your blood sugar levels. If your doctor is concerned about the results, he or she may recommend that you have a glucose tolerance test later in your pregnancy, since higher-than-average blood sugar levels mean you are more likely to develop gestational diabetes.
The glucose tolerance test
According to your doctor's instructions, you should not eat or drink anything for 8 to 14 hours before the blood sugar test (except for a little water). When you come to the office, the first blood test he or she will do is a fasting blood sugar test to determine the amount of sugar in your blood on an empty stomach. Next, you will have to drink a sugary syrup, which may be hard to swallow, depending on your sugar cravings. Finally, the doctor will do two more blood tests. The first-hour blood sugar test is one hour after you drink the syrup; the second-hour test is two hours after that.
In summary
The gestational diabetes screening test involves drinking a sugary syrup and taking a blood test one hour later. The glucose tolerance test involves taking a blood test on an empty stomach and then taking a sugary syrup. This is followed by two more blood tests one hour apart.
How to prepare for these tests?
Generally, you do not need to change your diet or do anything special to prepare for these tests. You will simply be asked to arrive at the glucose tolerance test fasting. Just tell your healthcare professional if you are taking any medication to make sure it does not interfere with the results of the blood tests.
Preparing for the Gestational Diabetes Screening Test
The gestational diabetes screening test does not require any special preparation; it is a simple blood test carried out in one hour and does not require fasting.
Preparing for the glucose tolerance test
Your healthcare provider will ask you to arrive at your glucose tolerance test fasting, which means you should not eat or drink anything for 8 to 14 hours before the blood sugar test (except for a small amount of water). You may find it most convenient to schedule your appointment in the morning so that you can have fasted since the night before. You will likely need to stay in the office or lab for these few hours. Bring a book or fully charge your phone while you wait.
In summary
No special preparation is necessary before either test: you can continue to eat normally. However, be aware that you will be asked to arrive at the glucose tolerance test on an empty stomach, meaning that you must not have eaten anything for 8 to 14 hours before the blood tests. It is advisable to make an appointment in the morning – you will simply have to not eat breakfast before the test. Finally, if you are already taking medication, inform your healthcare professional.
Do gestational diabetes and glucose tolerance tests have side effects?
There are no reported side effects for most pregnant women, either during or after either of these two tests. You may feel a little nauseous or flushed right after drinking the sugar solution, but that's normal. Some women find the liquid too sweet and hard to swallow. Finally, these tests involve blood draws, which means you may feel dizzy and have a bruise near the sample site, but other than that, the risks associated with these tests are minimal.
In summary
For most pregnant women, there are no side effects to report after either of these two tests. However, some women may find the solution too sweet and experience mild nausea or hot flashes. Finally, the blood test may cause mild dizziness and the appearance of a bruise at the injection site.
How to interpret your test results?
Because the normal range for gestational diabetes screening (one-hour) and glucose tolerance (two-hour) test results can vary by lab or hospital, your doctor is the best person to talk to if you need information or advice about your results and recommended next steps. However, the following general guidelines may apply:
Gestational Diabetes Screening Test Results
In general, a blood sugar level below 1.26 g/L (7 mmol/L) is considered normal. This result is expressed either in grams per liter or millimoles per liter, which in both cases correspond to an amount of matter (in this case, sugar) in a given volume of blood. If your blood sugar level is considered normal, you do not have gestational diabetes. If, on the contrary, your blood sugar level is higher than this value, your healthcare professional will have you take a glucose tolerance test later in your pregnancy, which will help determine whether you do indeed have gestational diabetes.
Glucose tolerance test results
First of all, it is important to remember that your healthcare professional is there to ensure that you are in good health and therefore uses the precautionary principle: if they ask you to take a glucose tolerance test, this does not mean that you have gestational diabetes but simply that they want to avoid unpleasant surprises. During this test, you will have three blood tests: one on an empty stomach when you arrive, one 1 hour after drinking a sugar solution and a final one 2 hours after drinking the solution.
The values considered normal following these analyses are as follows:
- Fasting: 0.92 g/L (5.1 mmol/L)
- After 1 hour: 1.80 g/L (10 mmol/L)
- After 2 hours: 1.53 g/L (8.5 mmol/L)
If the result of one of the tests is higher than normal, another test four weeks later may be recommended. If the results of at least two of the tests are higher than normal, your healthcare professional may diagnose gestational diabetes.
If your diagnosis is positive, your healthcare professional will be able to explain what to do to avoid complications. A healthy diet and some daily physical activity , as well as treatment if necessary, will help you control the evolution of your blood sugar levels and keep you and your baby healthy.
In summary
Blood sugar levels considered normal vary depending on the test performed. For a gestational diabetes screening test, a blood sugar level above 1.26 g/L (7 mmol/L) indicates a risk of diabetes. You will then do a glucose tolerance test, which consists of several blood tests. Depending on the number of results above normal, your healthcare professional may conclude that you have gestational diabetes. Don't panic, however, as in many cases this is just a formality to avoid unpleasant surprises.
FAQ AT A GLANCE
How is the gestational diabetes test performed during pregnancy?
Pregnancy can trigger temporary diabetes, called gestational diabetes, in pregnant women. It is diagnosed in two stages: a first test, called screening, is mainly used to identify whether you are at risk or not; a second test, called tolerance, is used to establish a diagnosis with more certainty. In both cases, blood tests are performed after absorption of a sugar solution to determine whether your body can absorb the sugar effectively.
When is the gestational diabetes test done?
Gestational diabetes screening is usually done between the 24th and 28th week of pregnancy. Depending on certain factors (age, weight, family history, etc.), your healthcare professional may suggest that you do it earlier.
Can I drink water before gestational diabetes test?
Thea first test, called screening, does not require any special precautions. You can drink water or have eaten before the test. The second test, called tolerance test, involves arriving on an empty stomach, therefore without having eaten, but you can drink a little water beforehand.
In summary
The gestational diabetes screening test is a routine test offered in all pregnancies. It involves measuring the amount of sugar in your blood and checking that it is not too high. If the values are too high, a complementary test, the glucose tolerance test, is carried out later in your pregnancy. This is slightly more complex (and requires you to fast) but allows us to determine more precisely whether you actually have gestational diabetes. In all cases, it is a disease that can be treated, in particular through a healthy diet, moderate physical activity and, if necessary, appropriate treatment. Before starting any physical activity, remember to ask your healthcare professional for approval.
Don't be put off by blood tests. They play an important role in ensuring the health of you and your baby. If you have any doubts about these tests and the meaning of the results obtained, your doctor will be able to provide you with all the necessary information.
