Oral Glucose Tolerance Test

Oral Glucose Tolerance Test

In the body of a woman carrying a child under her heart, sometimes such dramatic changes can negatively affect her health and well-being. In addition to toxicities, edema, anemia, and other troubles, carbohydrate metabolism disorders, classified as gestational diabetes (GDM), can also occur. A glucose tolerance test during pregnancy helps to identify or exclude such conditions. In this article, we will give you a complete guide about oral glucose tolerance tests. In this article, we will give you full-on information about the oral glucose tolerance test.

Oral Glucose Tolerance Test

According to the Ministry of Health protocols, all expectant mothers should undergo this study for 24 to 28 weeks. The most important sugar curve analysis in pregnancy is for women who are at risk. For example, if there are recorded cases of diabetes in the family or the patient herself has already had problems with carbohydrate metabolism. It is worth examining expectant mothers, in whose urine analysis glucose was found. Overweight women are also at risk.

The Oral Glucose Tolerance Test (GTT) in pregnant women with risk factors is carried out immediately after registration. Then again, from 24 to 28 weeks. Indicating the dosage of the monosaccharide.

There are also several contraindications to GTT:

  • Glucose loading is contraindicated in women whose fasting blood sugar exceeds 7.0 mmol / L (in some laboratories, 5.1 mmol / L).
  • In the third trimester, after a gestation period of 28 weeks, the carbohydrate load poses a danger to the fetus.
  • The test is not performed for inflammatory processes, infections, exacerbation of pancreatitis, dumping syndrome.
  • It is pointless to conduct a study on impaired glucose tolerance against a pharmacotherapy background with drugs that increase glycemia.
  • For pregnant women with severe toxicosis, the test is dangerous in several consequences. Carbohydrate loading is not very pleasant and can only exacerbate nausea and other symptoms.

Preparing for testing

For the results of the Oral Glucose Tolerance Test during pregnancy to be reliable, you need to prepare for the study properly. It is important not to change your usual diet for three days before GTT, to eat enough carbohydrate foods. A regular regimen of physical activity during this period is also required. The night before the oral glucose tolerance test, only water is allowed for at least 8 hours. It is important to give up alcohol altogether 11-15 hours before the study.

If you follow a number of these mandatory rules, the GTT will pass naturally, and the results will be reliable. It is better to contact your doctor to tell you in detail how to take the two-hour test correctly. It is also worth consulting with him about the likely risks, harm to the unborn child, the feasibility of research, and the possibility of abandoning it.

GTT procedure

How to take a glucose tolerance test during pregnancy? First, you should properly prepare for the study, following all the doctor’s recommendations. Testing begins with taking blood for analysis from a vein on an empty stomach and fixing the sugar level, then carrying out a carbohydrate load.

The simplest option is an oral glucose tolerance test (OGTT) when the patient drinks a glucose solution with water in 5 minutes. According to specific indications, when such a test cannot be carried out. The dosage of monosaccharides in different laboratories is different. It happens 75g or 100g. It is up to the doctor to determine this. After the carbohydrate load, sugar values ​​are measured in two stages: after 1 hour, then after 2 hours. If the sugar curve values during pregnancy are outside the normal range, this may sign gestational diabetes.

Decoding and interpretation of results

WHO establishes diagnostic criteria for glycemic disorders. Indicators of the norm of glucose in blood plasma from a vein (load of 75 g):

  • in the morning on an empty stomach – less than 5.1 mmol / l,
  • after 1 hour – less than 10 mmol / l,
  • after 2 hours – less than 8.5 mmol / l.

The following indicators determine impaired glucose tolerance (IGT):

  • in the morning on an empty stomach – from 5.1 to 7 mmol / l,
  • or an hour after carbohydrate load – 10 mmol / l or more,
  • or after two hours – from 8.5 to 11.1 mmol / l.

Plasma carbohydrate levels above normal are indicative of gestational diabetes. However, during pregnancy, an abnormal sugar curve is also a false positive result associated with recent surgery, acute infection, certain medications, and severe stress. To avoid misdiagnosis of impaired glucose tolerance, you need to follow the preparation rules for testing and inform your doctor about factors that distort the results.

Also Read: Steps to Take When Starting Your Own Gym

Should you even agree to test?

Taking an oral glucose tolerance test during pregnancy is a concern for many women. Expectant mothers are afraid that this will hurt the fetus. The procedure itself often brings unpleasant sensations in the form of nausea, dizziness, and other symptoms. Not to mention that it is necessary to allocate at least 3 hours for the glucose load test in the morning, during which you cannot eat. This is why it is not uncommon for pregnant women to want to refuse research.

However, it would help if you realized that it is better to coordinate. Such a decision with your doctor. He will assess the study’s feasibility on various factors, including how long the patient is, how the pregnancy proceeds, etc. Therefore, refusal to test seems justified for pregnant women who belong to this category.

To qualify as low risk, all of the following statements must be true:

  • You have never had a situation where a test showed that your blood glucose level was higher than usual.
  • Your ethnic group has a low risk of diabetes.
  • You do not have a first-degree relative (parent, brother, or child) with type 2 diabetes.
  • You are under 25 and of average weight.
  • So you have not had bad GTT results in a previous pregnancy.

Consider the implications of undiagnosed gestational diabetes before abandoning testing. It carries with it a high incidence of complications for the baby and the mother herself. It increases the risk of developing type 2 diabetes in a woman in labour over time. Statistics say that about 7% of women in a position face this problem. Therefore, if there is even the slightest concern, it is better to determine the glycemic profile.

Oral glucose tolerance test during pregnancy: when and how to take it?

From the beginning of pregnancy, significant changes in metabolic processes, including carbohydrate, occur in a woman’s body. To detect violations of the latter, the determination of blood sugar level. Compared to men, diabetes mellitus among women is much more common, and there is a clear association between the gestational period and childbirth – GDM (gestational diabetes mellitus).

Also Read: Flu Symptoms And Treatment

Methods for detecting impaired carbohydrate metabolism

The prevalence of diabetes among pregnant women are on average, 4.5% in Russia in their total number. In 2012, the Russian National Consensus defined GDM and recommended new criteria for its diagnosis and treatment and postpartum follow-up for practical application. But does not meet the standards adopted for a newly diagnosed (manifest) disease.

These criteria are as follows:

  • the fasting sugar content is more significant than 7.0 mmol / l (hereinafter the same names of units of measurement) or equal to this value;
  • glycemia, confirmed in re-analysis, which at any time throughout the day and regardless of diet is equal to or greater than 11.1.

Also Read: Foods Rich In Magnesium

In particular, if a woman’s fasting venous plasma sugar level is less than 5.1, and with an oral glucose tolerance test, 1 hour after exercise is less than 10.0, after 2 hours – less than 8.5, but more than 7.5 – these are normal options for a pregnant woman. At the same time, for non-pregnant women, these results indicate a violation of carbohydrate metabolism.

How long does a glucose tolerance test take during pregnancy?

The detection of carbohydrate metabolism disorders is carried out in stages:

  1. Stage I of the survey is mandatory.
  2. At stage II, an oral glucose tolerance test with 75 grams of glucose is carried out at 24-28 weeks of gestation (optimally 24-26 weeks). In certain cases (see below), such a study is possible up to 32 weeks; if there is a high risk – from 16 weeks.

Stage I consists of conducting a laboratory study of glucose in blood plasma on an empty stomach after an 8-hour (at least) fast. A blood test is also possible, regardless of the diet. But the blood glucose level is less than 11.1. This is an indication for repeating the study on an empty stomach.

Also Read: Is Alkaline Water Good For You

Suppose the test results meet the criteria for newly diagnosed (manifest) diabetes. For further monitoring and appropriate treatment. In fasting glucose above 5.1.


A glucose tolerance test is performed for all women in the following cases:

  • Absence of deviations from the norm in the results of a phase I examination in early pregnancy.
  • The presence of at least one of the signs of a high risk of GDM, ultrasound signs of abnormalities in carbohydrate metabolism in the fetus, or specific ultrasound dimensions of the fetus. In this case, the test is possible inclusively for the 32nd week.

Signs of high risk include:

  • the high degree of obesity: body mass index is 30 kg / m2 and above.
  • The presence of diabetes mellitus in the closest (first generation) relatives.
  • The presence in the past of gestational diabetes mellitus or any carbohydrate metabolism disorders.

Is a glucose tolerance test dangerous during pregnancy?

This study poses no risk to women and fetuses up to 32 weeks of age. Carrying it out after the specified period can be dangerous for the fetus.

Testing is not carried out in the following cases:

  • early toxicosis of pregnant women.
  • Compliance with bed rest.
  • The presence of diseases of the operated stomach.
  • The presence of chronic cholecystopancreatitis in the acute stage.
  • So the presence of an acute infectious or acute inflammatory disease.

Also Read: Relax and Unwind: The Best CBD Capsules for 2021


Conditions for the glucose tolerance test include:

  • Typical food for the previous 3 (at least) days with a daily carbohydrate content of at least 150 g in the diet.
  • Mandatory carbohydrate content in the amount of 30-50 g in the last meal.
  • Fasting (but not limiting water intake) for 8-14 night hours on the eve of testing.
  • Exclusion (if possible) of taking medications containing sugar (pharmaceuticals of vitamins and iron, antitussives, etc.). As well as beta-blocking, beta-adrenomimetic, and glucocorticosteroid drugs.
  • A doctor’s warning about a test while taking progesterone.
  • Smoking cessation and sitting position of the patient until the end of the test.

Also Read: Symptoms Of Low Potassium

Stages of the

They consist of:

  • Taking the first blood sample from a vein and conducting its analysis. Suppose the results indicate the presence of newly diagnosed or gestational diabetes mellitus.
  • Carrying out a sugar load with average results of the first stage. It consists of the patient taking 75 g of glucose powder, dissolved in 0.25 litres of warm (37-40 ° C) water, for 5 minutes.
  • Subsequent sampling and analysis of the next samples after 60 minutes, and then after 120 minutes. Suppose the second test result indicates the presence of GDM.

Also Read: Blood Clots In Urine

features of the procedure and preparation

The optimal time is 24 weeks. If the patient at the first visit to the antenatal clinic identified risk factors for gestational diabetes.

The risk group for metabolic disorders includes women with:

  • a history of hyperglycemia.
  • Glucosuria – sugar content in urine.
  • Fetopathy of the fetus, polyhydramnios according to ultrasound.
  • Stillbirth, large fetus, or gestational diabetes mellitus in previous pregnancies.
  • Obesity.
  • Excess weight gain during pregnancy.
  • Burdened by heredity, etc.

 The main reasons to refuse the test:

  • fasting hyperglycemia more than 5.1 mmol / l.
  • previously diagnosed diabetes mellitus (if the diagnosis is relevant).
  • Acute illness or exacerbation of chronic pathology.
  • A course of taking drugs that increase the level of glycemia (for example, steroids).
  • Gestational age of more than 32 weeks.

If there are no contraindications, then the woman is assigned a specific examination date. At least 3 days before the analysis, a regular diet with a sufficient amount of complex and simple carbohydrates is recommended.