While expecting a child, global changes occur in the body of the expectant mother. During this period, it is important to carefully monitor changes in health status and monitor any deviations. Modern medicine offers multiple procedures to prevent possible problems.

What is a glucose tolerance test done during pregnancy?

A glucose tolerance test is an important examination for an expectant mother. Thanks to the results, the doctor determines the ratio of glucose in the blood, this helps to identify a tendency to certain diseases and prevent their development. When is the test done? How should you prepare?

What is a glucose tolerance test?

A glucose tolerance test (GTT) is a test to determine the body’s tolerance to glucose (sugar), shows whether all processes are occurring correctly and identifies a predisposition to gestational diabetes. Be sure to prescribe for patients at risk:

• during difficult pregnancy;
• having diabetes mellitus;
• overweight.

GTT is a safe procedure for the mother and child.

But there are contraindications:

• kidney and liver diseases;
• in the presence of infections and viral diseases;
• dumping syndrome;
• endocrine system problems;
• when taking certain medications;
• after 32 weeks of term.

If a woman in labor is prescribed bed rest, then the test is not done at this time, but only at the end of it, if there are no other contraindications.

Why during pregnancy

GTT is necessary to determine predisposition to gestational diabetes, which develops during pregnancy. The body is overloaded and cannot cope with metabolic reactions, and as a result, a disease develops. It is dangerous for the mother and the child. The peculiarity of the disease is the absence of symptoms, so it is extremely difficult to notice it without conducting an examination. If treatment is ignored, after the birth of a child, the disease can develop into manifest type 2 diabetes mellitus.

In the 1st trimester

The first trimester is fundamental; the laying and formation of the child’s organs and vital systems occurs. The placenta begins to actively develop, but does not yet have high protective functions, which is why harmful elements and substances can reach the fetus. That is why in the first weeks you need to listen especially carefully to the signals of the body, to any changes.

GTT is not done at the beginning of pregnancy, it is pointless. Insulin resistance in pregnant women increases only in the middle of pregnancy. The doctor can prescribe the earliest GTT starting from the sixteenth week of pregnancy.

In the second trimester

Optimal time for the procedure. The best range is 24-26 weeks of pregnancy. But if certain factors are present, there is a need for an earlier test:

• excess body weight;
• history of difficult pregnancies;
• sugar in urine;
• diabetes mellitus in close relatives;
• large fruit;
• increased blood glucose levels.

Is it done in the third trimester?

In the last weeks, GTT is done strictly as prescribed by the treating doctor. After 32 weeks, an additional glucose load is unsafe for the baby, so this is the deadline.

How to prepare for tests

Venous blood is used for the test. The patient needs to prepare for the analysis.

For several days before the GTT, you should not engage in physical activity that requires great effort.

What not to eat

On the eve of the examination, you need to reduce the amount of fatty foods. But, in general, you should not change your diet much, otherwise this may cause an incorrect result. The amount of carbohydrates consumed is at least 150 g per day. Eight hours before the test, you are prohibited from eating, only plain water. Consumption of alcohol and cigarettes is not allowed.

If the patient uses medications, it is necessary to notify the specialist in advance. He must adjust the dose of medications to ensure that the test results are not affected.

When is it available, what time of day?

The examination takes place in the morning. The procedure takes several hours, so this time of day is most preferable.

At what week of pregnancy is it done?

If the pregnancy is normal and the woman has no health problems, the test is performed mid-term in the range from 24 to 26 weeks, but no later than 32. In case of certain abnormalities or risks, the doctor may prescribe a glucose tolerance test no earlier than 16 weeks .

How many times during pregnancy should you do it?

The number of glucose test procedures depends on the general condition of the woman in labor. If it's ok, then once is enough. If there are problems or abnormalities, the doctor prescribes examinations for as long as necessary. No earlier than the sixteenth week of pregnancy and no later than the thirty-second.

How is blood tested for impaired glucose tolerance?

The examination procedure takes a couple of stages:

1. On an empty stomach, blood is taken from a vein and an analysis is done. If the glucose level is increased, then the patient experiences gestational diabetes. The test is completed and the woman in labor is sent to the attending doctor with the results of the analysis.
2. When the result is satisfactory, the indicators are normal, the patient should drink a glass of glucose (75 g of dry glucose diluted with 200-300 ml of warm water). An hour later, the doctor takes blood from the vein again.
3. If the indicators are stable and do not exceed the permissible norm, the test can be repeated after two or three hours - this is called the O’Sullivan test.

The results of the study are immediately reported to the patient.

If GTT is reduced: reasons

A low rate is also not the norm and poses a danger to the woman and child. Glucose plays an important role in nutrition, so levels are checked periodically during pregnancy. Low sugar is rare, called glycemia, and this is facilitated by:

• severe toxicosis;
• poor nutrition;
• disorders in the gastrointestinal tract.

With acute glucose deficiency, the patient's condition deteriorates sharply and the question of terminating the pregnancy may arise. You need to take this problem seriously and follow your doctor’s recommendations.

What to do if the GTT level is increased

If the glucose level is elevated, a pregnant woman needs to constantly monitor the amount of sugar in the blood, adhere to a diet and perform special physical exercises. Sometimes the patient is prescribed insulin therapy.

Diet rules for gestational diabetes:

• drink at least 1.5 liters of water daily;
• Fried, sweet, spicy, fatty foods are prohibited;
• exclude fast food;
• Do not use sauces: mayonnaise, ketchup;
• focus on foods containing fiber;
• Recommended lean meat: turkey, chicken;
• Divide meals into 5-6 times, three main meals and snacks.

Decoding the indicators from the table

	Venous whole blood glucose concentration mg/dL	Whole capillary blood	Venous plasma
Diabetes mellitus
On an empty stomach	>6,1(110)	>6,1(110)	>7,0(126)
	>10,0(180)	>11,1(200)	>11,1(200)
Impaired glucose tolerance
On an empty stomach	<6,1(110)	<6,1(110)	<7,0(126)
Two hours after taking glucose	<6,7(120)< <10(180)	>7,8(140)< <11,1(200)	>7,8(140)< <11,1(200)
Increased fasting plasma glucose levels	<5,6(100)< <6,1(110)	>5,6(100) < <6,1(110)	>6,1(110) < <7,0(126)
Norm
On an empty stomach	<5,6(100)	<5,6(100)	<6,1(110)
After taking glucose	<6,7(120)	<7,8(140)	<7,8(140)

Normally, the glucose level is 7 mmol/l and slightly lower. Exceeding this level means the development of gestational diabetes in the patient.

After taking the sweet solution, the indicators should increase sharply, and after a two-hour period they return to normal, if there are no pathologies.

Normal indicators vary and are very arbitrary, so a specialist makes a conclusion about the patient’s condition.

What to do

With gestational diabetes, a woman needs to regularly visit a doctor and take tests to monitor blood glucose, plus:

• balanced diet;
• moderate physical activity;
• blood pressure control;
• maintaining a daily routine and a healthy lifestyle.

In some cases, it is necessary to take medications, prescribed by the attending doctor. The expectant mother can take insulin, but it is also strictly according to the recommendations and it is necessary to measure the amount of glucose with a special device - a glucometer.

Tablets that help lower sugar are prohibited for pregnant women!

Dangerous moments

High glucose levels are dangerous throughout pregnancy, both for the woman and the child. Provokes the following diseases and abnormalities in the fetus:

• hypoxia, respiratory dysfunction;
• jaundice;
• lack of magnesium and calcium in the blood;
• violation of proportions;
• large fruit size.

For a woman in labor, the disease is dangerous:

• polyhydramnios;
• complications throughout pregnancy;
• dysfunction of the cardiovascular system;
• provokes the development of infectious diseases of the genital tract, which also affects the intrauterine development of the child;
• miscarriage, premature birth;
• development of diabetes mellitus after childbirth.

Due to the fact that the fetus is generally larger than normal, delivery is possible only with the help of cesarean lumen.

One of the important points is the patient’s condition after childbirth. It is necessary to carefully monitor glucose levels to prevent the development of diabetes.

Carrying a child is a difficult and difficult period in a woman’s life. It is important to pay timely attention to your health and not ignore the doctor’s recommendations and undergo prescribed procedures. The glucose tolerance test is one of the most important and safe for the expectant mother and child.

Useful video

The body of a woman carrying a child sometimes undergoes such drastic changes that can negatively affect her health and well-being. In addition to toxicosis, edema, anemia and other troubles, carbohydrate metabolism disorders, classified as gestational diabetes (GDM), may also appear. A glucose tolerance test during pregnancy helps to identify or exclude such conditions.

Indications and contraindications

According to the Ministry of Health protocols, all expectant mothers should undergo this study between 24 and 28 weeks. The analysis of the sugar curve during pregnancy is most important for women who are in the risk category. For example, if there are documented cases of diabetes in the family or the patient herself already had problems with carbohydrate metabolism. Expectant mothers whose urine tests have detected glucose should be examined. Overweight women are also at risk.

A glucose tolerance test (GTT) in pregnant women with risk factors is carried out immediately after registration, then again from 24 to 28 weeks.

A referral for examination is given by the attending physician, indicating the dosage of the monosaccharide. There are a number of contraindications to GTT:

• Glucose loading is contraindicated in women whose fasting blood sugar level exceeds 7.0 mmol/L (5.1 mmol/L in some laboratories).
• The test is not performed on patients under 14 years of age.
• In the third trimester, after the gestation period of 28 weeks, the carbohydrate load poses a danger to the fetus, therefore it is carried out strictly according to the doctor’s indications. After 32 weeks it is never prescribed.
• The test is not performed for inflammatory processes, infections, exacerbation of pancreatitis, dumping syndrome.
• It makes no sense to conduct a study for impaired glucose tolerance against the background of pharmacotherapy with drugs that increase glycemic levels.
• For pregnant women with severe toxicosis, the test is dangerous due to a number of consequences. Loading with carbohydrates doesn't feel good and can only make nausea and other symptoms worse.

Preparing for testing

In order for the results of a glucose tolerance test during pregnancy to be reliable, you need to properly prepare for the test. It is important not to change your usual diet for three days before GTT, eat enough carbohydrate foods. The usual regime of physical activity during this period is also required. The night before the glucose tolerance test, you are only allowed to drink water and not eat food for at least 8 hours. It is important to completely abstain from alcohol 11–15 hours before the test. Smoking is also prohibited during this time. The last meal should include at least 30 g of carbohydrates.

If you follow a number of these mandatory rules, the GTT test will go smoothly and the results will be reliable. It is better to contact your doctor so that he can 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 the study and the possibility of refusing it.

Procedure for conducting GTT

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 from a vein on an empty stomach for analysis and recording the sugar level, then carrying out a carbohydrate load. Some laboratories will first take a finger prick sample and measure your glucose levels using test strips. If the resulting value exceeds 7.5 mmol/l, carbohydrate loading is not carried out.

The simplest option is an oral glucose tolerance test (OGTT), when the patient drinks a solution of glucose with water in 5 minutes. For certain indications, when such a test cannot be performed, for example, due to severe toxicosis, glucose is administered intravenously. The dosage of the monosaccharide in different laboratories is different, it can be 75g or 100g. It is up to the doctor to determine this.

After a carbohydrate load, sugar levels are measured in two stages: after 1 hour, then after 2 hours. Smoking and increased physical activity are prohibited until testing is completed. If your blood sugar readings are outside the normal range during pregnancy, this may be a sign of gestational diabetes. However, a definitive diagnosis can only be made after consulting an endocrinologist. To clarify the severity of carbohydrate metabolism disorders, a blood test for glycated hemoglobin is prescribed.

Decoding and interpretation of results

Diagnostic criteria for glycemic disorders are established by WHO. Indicators of normal 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.

Impaired glucose tolerance (IGT) is determined by the following indicators:

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

Indicators of carbohydrate levels in the blood plasma above normal indicate gestational diabetes. However, an abnormal sugar curve during pregnancy is sometimes a false positive result associated with recent surgery, acute infection, taking certain medications, or severe stress. To avoid misdiagnosis of impaired glucose tolerance, you need to follow the rules of preparation for testing and tell your doctor about factors that can distort the results.

A clear indicator of diabetes mellitus is exceeding the limit of 7 mmol/l in a sample taken on an empty stomach or the limit of 11.1 mmol/l in any other sample.

Is it worth agreeing to testing at all?

Taking a glucose tolerance test during pregnancy is a concern for many women. Expectant mothers are afraid that this will have a negative impact on the fetus. The procedure itself often brings discomfort in the form of nausea, dizziness, and other symptoms. Not to mention that you need to allocate at least 3 hours from the very morning for a glucose load test, during which you cannot eat. This is why pregnant women often want to refuse the study. However, you should realize that it is best to discuss this decision with your doctor. He will evaluate the feasibility of the study based on various factors, including how far along the patient is, how the pregnancy is progressing, etc.

Unlike us, in Europe and the USA, women with a low risk of developing glycemic disorders are not screened for glucose. Therefore, refusing testing seems justified for pregnant women who fall into 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 normal.
• Your ethnic group has a low risk of diabetes.
• You do not have a first-degree relative (parent, sibling, or child) with type 2 diabetes.
• You are under 25 years old and of normal weight.
• You did not have poor results on GTT during a previous pregnancy.

Before you decide not to get tested, consider the consequences of undiagnosed gestational diabetes. It carries with it a high incidence of complications for the baby and the mother herself, and increases the risk of developing type 2 diabetes in the mother over time.

A glucose tolerance test during pregnancy is an analysis that allows you to monitor an important indicator of the condition of a woman’s body - the level of glucose in the blood. Basically, the sugar test is carried out in relation to the detection of diabetes.

The analysis should not be confused with a hemotest, which identifies individual food intolerances.

Women who have relatives suffering from diabetes are at risk. In this case, for a pregnant woman, undergoing GTT is a mandatory precaution.

It is enough to undergo it once, when there is no obvious suspicion of diabetes and the result is negative. However, it is possible to take the test again during pregnancy if there is a suspicion of increased blood glucose.

Why do they do it?

Often, expectant mothers ask doctors why they are prescribed a glucose tolerance test if they are not at risk. If elevated blood sugar levels are detected, a number of measures are prescribed that are acceptable during pregnancy.

Prescribed to everyone as a preventive measure

Carrying a child is a time of great change in a woman. But these changes are not always for the better. The body undergoes serious changes while carrying a future baby.

Considering the heavy loads that the body as a whole undergoes, some pathologies appear exclusively while expecting a child. Diabetes mellitus is one of these diseases.

In these situations, pregnancy serves as a provoking factor for the latent course of the disease. Therefore, as a preventive measure, GTT analysis during pregnancy is necessary and important.

How to take it

The first logical question that women ask during pregnancy is at what period of time GTT is performed. A glucose tolerance test is done in the first trimester along with a number of other tests.

In order to properly undergo the examination, you must carefully prepare:

• exclude nervous disorders;
• limit physical activity;
• do not make significant changes in the diet - eat as usual (do not follow any diets);
• do not eat food (within 8 hours before the test).

The test is not performed if there are any diseases in the acute stage, even in the case of a common runny nose. Any changes of this kind will greatly affect the results of the study, so these options must be excluded.

GTT is done on an empty stomach (you can drink water, but not during testing). It is carried out by drawing blood from a vein 3 times, with an interval of 1 hour between the second and third sampling:

1. First, blood is drawn.
2. After this, a special sweet liquid (glucose syrup of a certain concentration) is drunk.
3. For the next hour, the patient should not eat, drink, or exercise - all this can greatly distort the test results.
4. The next blood draws are carried out an hour and two after the first analysis.
5. After this time, after taking the cocktail, the blood sugar level in a healthy person returns to normal. This is what the test results should reflect.

Must consult a doctor

If the readings are high and not within normal limits, an immediate consultation with a doctor monitoring the pregnancy is prescribed. If the first test shows an elevated sugar level, a repeat appointment will most likely be scheduled to rule out a possible error.

There are a number of reasons why a false result is possible:

• the eight-hour diet was not followed before donating blood;
• significant changes in diet during the three days before the test (increased or insufficient carbohydrate intake);
• carbohydrate metabolism disorders;
• excessive physical activity;
• stressful condition;
• infectious diseases (including respiratory acute respiratory viral infections, acute respiratory infections);
• taking any medications that affect carbohydrate metabolism (warn your doctor about the use of medications).

GTT norms

Numerical indicators of 7 mmol/l and below are within normal limits. If elevated levels are observed, a diagnosis of gestational diabetes is usually made. This type of disease occurs in 14% of women.

The figure 7 mmol/l is very arbitrary. GTT norms for pregnant women are presented in the table below:

The observed dynamics are normally maintained, but the numbers may be different depending on various factors.

It is worth noting that the upper limit - the maximum permissible indicator - is also very arbitrary. And in different sources the numbers vary. Therefore, no independent interpretations; only a qualified doctor observing your pregnancy will be able to interpret the results correctly and say about the presence of a possible disease or its absence.

Glucose thresholds

Gestational pathology is called because before pregnancy the woman did not show any signs of diabetes. After childbirth, when the body is restored, the glucose level either returns to normal, or diabetes develops into another type - T1DM (type 1 diabetes), or it turns out that the pregnant woman has T2DM (type 2 diabetes).

If a woman has problems with carbohydrate metabolism earlier before pregnancy or already during pregnancy, it is better to take a glucose tolerance test at 25 weeks to identify possible deviations from the norm.

Depending on the method of introducing the glucose load into the body, two types of analysis are distinguished: oral (or oral) and intravenous. The second method is more often used if the patient for some reason cannot take the “sweet cocktail” orally.

The OGTT analysis is carried out with a load - consuming 75 g of glucose dissolved in a glass of water. To be sure, there should be no significant changes in the pregnant woman’s diet for three days before donating blood. In some cases, women donate blood from a vein without ingesting a glucose cocktail.

Repeated checks may be ordered

The study is not just for adults. This method is also used for children over 14 years of age. The difference lies in the amount of load taken and in the numerical indicators included in the normal range.

For children under 14 years of age, analysis without load is acceptable. The norms differ only up to the age of five; later they correspond to adult values ​​from 3.3 to 5.5 mmol/l. Up to a year, the level fluctuates around 2.8 – 4.4 mmol/l.

It is worth noting that the presence of elevated blood glucose does not necessarily indicate diabetes mellitus in the patient; it may be a sign of disorders such as:

• overactive thyroid gland;
• increased hormonal activity of the adrenal glands;
• taking glucocorticoids for a long time;
• pathology of the pancreas.

Low glucose levels - hypoglycemia - occur in a number of isolated cases. Low sugar is usually associated with an overdose of insulin medications in diabetes.

Why is it dangerous?

The analysis itself is not dangerous. This applies to the no-load test.

In relation to exercise testing, it is possible to “overdose” blood sugar levels. This happens only when the pregnant woman already has a high glucose level, but there will be symptoms that clearly indicate a violation of carbohydrate metabolism.

OGTT is not carried out just like that. During pregnancy with exercise, the test is performed a maximum of 2 times and only in case of serious suspicion of diabetes. While blood is donated once a trimester without fail, so the blood sugar level can be found out without additional stress.

Eat different fruits

Like any medical procedure, GTT has a number of contraindications, including:

• congenital or acquired glucose intolerance;
• exacerbation of chronic stomach diseases (gastritis, disorders, etc.);
• viral infections (or pathologies of another nature);
• severe toxicosis.

In the absence of individual contraindications, the test is safe even during pregnancy. In addition, judging by the reviews, it does not present any particular discomfort when performed.

Women describe a glucose cocktail as “just sweet water,” which is easy to drink. Of course, if the pregnant woman does not suffer from toxicosis. The need to draw blood 3 times within two hours leaves a slight discomfort.

However, in most modern clinics (Invitro, Helix), blood is taken from a vein completely painlessly and does not leave any unpleasant impressions, unlike most municipal medical institutions. Therefore, if there are any doubts or concerns, it is better to take the test for a fee, but with the proper level of comfort.

Don't worry - everything will be fine

In addition, you can always administer glucose intravenously, but to do this you need to inject it again. But you won't have to drink anything. Glucose is introduced gradually over 4-5 minutes.

Testing is contraindicated for children under 14 years of age. For them, it is carried out exclusively by drawing blood without being burdened by a glucose load.

Mirror belly
pregnant fruit analysis
passed

The volume of the sweet cocktail taken is also different. If the child weighs less than 42 kg, the dose of glucose is reduced.

Thus, the test does not pose a threat if you prepare properly and follow the instructions. And undiagnosed diabetes poses a danger to the fetus and mother.

Proper metabolism, including carbohydrate metabolism, is important for the development of the fetus and for the mother’s body during pregnancy. The detected pathology is subject to correction, which will certainly be prescribed by the observing obstetrician-gynecologist.

The presence of gestational diabetes complicates pregnancy and future births. Therefore, it is so important to register it at the initial stage and make changes that help normalize blood sugar levels and minimize the harm from the disease.

Therefore, when prescribing this test, expectant mothers should not worry, but pay due attention to the test. After all, prevention is the best treatment, especially when we are talking not about one life, but about two at the same time.

: Borovikova Olga

gynecologist, ultrasound doctor, geneticist

An oral glucose tolerance test, carried out during pregnancy, consists of determining the level of plasma glucose on an empty stomach, one and two hours after a carbohydrate load in order to diagnose a disorder of carbohydrate metabolism (gestational diabetes mellitus).

Synonyms Russian

• Oral glucose tolerance test (OGTT)
• Glucose tolerance test
• Test with 75 grams of glucose

English synonyms

• Glucose tolerance test (GTT)
• Oral glucose tolerance test (OGTT)

Research method

Enzymatic UV method (hexokinase).

Units of measurement

Mmol/l, mg/dl (mmol/l*18.02=mg/dl).

What biomaterial can be used for research?

Venous blood.

How to properly prepare for research?

• An oral glucose tolerance test during pregnancy should be performed in the morning against the background of at least 3 days of unrestricted nutrition (more than 150 g of carbohydrates per day) and normal physical activity.
• The test should be preceded by an overnight fast for 8-14 hours (you can drink water).
• The last evening meal should contain 30-50 g of carbohydrates. Do not drink alcohol 10-15 hours before the test.
• Do not smoke the night before the test and until it is over.

When should an oral glucose tolerance test not be performed during pregnancy?

• Against the background of any acute disease, including infectious.
• While taking medications that increase glycemic levels (glucocorticoids, thyroid hormones, thiazides, beta blockers). It is required (preferably) to cancel them 3 days before the test.
• If you are more than 32 weeks pregnant.
• For pregnancy periods from 28 weeks to 32 weeks, OGTT is strictly according to the doctor’s instructions.

General information about the study

After taking blood on an empty stomach, the subject should drink 75 g of anhydrous glucose or 82.5 g of glucose monohydrate dissolved in 250-300 ml of water within no more than 5 minutes. Smoking and vigorous physical activity are not allowed during the test. After 1 and 2 hours, blood is taken again. It should be remembered that if the fasting blood glucose level exceeds 5.1 mmol/l, then an oral glucose tolerance test is not performed during pregnancy, since this blood glucose level itself is one of the criteria for diagnosing gestational diabetes mellitus.

An oral glucose tolerance test during pregnancy makes it possible to diagnose carbohydrate metabolism disorders during pregnancy (gestational diabetes mellitus), but a final diagnosis is possible only after a mandatory consultation with an endocrinologist.

When is the study scheduled?

• In case of questionable glycemic values, to clarify the state of carbohydrate metabolism during pregnancy.

What do the results mean?

Reference values

DIAGNOSTIC CRITERIA FOR DIABETES MELLITUS AND OTHER GLYCEMIC DISORDERS (WHO, 1999-2013)

Reasons for increased plasma glucose levels:

• carbohydrate metabolism disorders (gestational diabetes mellitus);
• false positive result – recent or ongoing acute illness, surgery or any other stressful situation, taking medications that increase glycemic levels (glucocorticoids, thyroid hormones, thiazides, beta blockers).

Reasons for low blood plasma glucose levels:

• taking medications that reduce glycemic levels (insulin, various sugar-lowering drugs);
• insulinoma;
• excessive fasting;



What tests are advisable to take for any positive result?oral glucose tolerance test:

1. In order to clarify the severity of carbohydrate metabolism disorders:

Literature

• Clinical recommendations "Algorithms for specialized medical care for patients with diabetes." Edited by I.I. Dedova, M.V. Shestakova, A.Yu. Mayorova 8th issue, M., 2017.
• Definition and diagnosis of diabetes mellitus and intermediate hyperglycemia. Report of a WHO/IDF ConsultatIon.2006.
• Recommendations for diabetes, prediabetes and cardiovascular diseases. EASD/ESC, Russian Journal of Cardiology 2014; No. 3(107):7-61.
• Gestational diabetes mellitus: diagnosis, treatment, postpartum care. Clinical recommendations (protocol) of the Ministry of Health of the Russian Federation. M., 2014.

Scientific editor: M. Merkusheva, PSPbSMU named after. acad. Pavlova, medical practice.
February, 2019.

Synonyms: glucose tolerance test, GTT, glucose tolerance test, sugar curve, Glucose tolerance test (GTT), Oral GTT in pregnancy

According to statistics, up to 14% of pregnant women are prone to gestational diabetes mellitus (impaired glucose tolerance). This is a serious medical problem that can lead not only to severe complications during pregnancy, but also to provoke the development of type II diabetes mellitus (DM) in a woman in the future.

The glucose tolerance test (GTT) makes it possible to timely detect pathological sugar levels in the expectant mother and prevent complicated pregnancy and the development of diabetes.

General information

Diabetes mellitus in pregnant women (gestational) has differences in comparison with the classic course of the disease. First of all, this concerns the quantitative indicators of the test - what predetermines a violation of carbohydrate metabolism for non-pregnant patients can be considered the norm for expectant mothers. That is why, to study pregnant women, a special glucose tolerance test is performed according to the O’Sullivan method. The analysis involves the use of a so-called “sugar load”, which makes it possible to identify the pathology of glucose absorption in the body.

Note: expectant mothers are at risk for developing diabetes. This is due to the restructuring of metabolic processes in the body, as a result of which disturbances in the absorption of one or another component are possible. In addition, gestational diabetes can be asymptomatic for a long time, so it is difficult to diagnose it without GTT.

Gestational diabetes itself is not dangerous and goes away on its own after the baby is born. However, if you do not provide supportive therapy that is safe for mother and baby, the risk of complications increases. Also among the dangerous consequences for women is the development of type II diabetes mellitus.

Gestational diabetes is associated with an increased risk of obesity, glucose intolerance, and type 2 diabetes in the offspring.

Timing of GTT in pregnant women

A glucose tolerance test should be performed at 16-18 weeks of pregnancy, but no later than 24 weeks. Earlier research will be uninformative, since insulin resistance (resistance) in expectant mothers begins to increase only in the second trimester. The test can be carried out from the 12th week if the patient has high sugar levels in a biochemical analysis of urine or blood.

The second stage of the examination is prescribed at 24-26 weeks, but no later than the 32nd, since at the end of the third trimester the sugar load can be dangerous for both mother and child.

If the results of the analysis coincide with the criteria for newly diagnosed diabetes, then the expectant mother is referred to an endocrinologist to prescribe effective therapy.

Indications

GTT is prescribed to all pregnant women to screen for gestational diabetes between 24 and 28 weeks of pregnancy.

A glucose tolerance test is prescribed for pregnant women up to 24 weeks who are at risk for:

The test is not advisable in the following cases:

• early toxicosis with pronounced symptoms;
• liver diseases;
• pancreatitis (inflammation of the pancreas) in acute form;
• peptic ulcers (damage to the inner lining of the digestive tract);
• stomach ulcer, gastritis;
• Crohn's disease (granulomatous lesions of the digestive tract);
• dumping syndrome (acceleration of the movement of stomach contents into the intestines);
• the presence of inflammatory, viral, infectious or bacterial diseases;
• late pregnancy;
• if necessary, strict bed rest;
• with a fasting glucose level of 7 mmol/l and above;
• while taking medications that increase glycemic levels (glucocorticoids, thyroid hormones, thiazides, beta blockers).

Decoding

Note: If at the first stage of the test the fasting blood glucose level exceeds 7 mmol/l, then additional diagnostics are carried out (determination of glycosylated hemoglobin, C-peptide) and a diagnosis of “diabetes mellitus of a certain type” (gestational, type 1, 2) is made. After this, an oral exercise test is prohibited.

There are a number of nuances to deciphering the test:

• only venous blood is indicative (it is not recommended to use arterial or capillary blood);
• established reference values ​​do not change with the duration of pregnancy;
• after exercise, one value is sufficient to diagnose gestational diabetes;
• if ambiguous results are obtained, the test is repeated after 2 weeks to exclude a false result;
• the analysis is repeated after childbirth to confirm or refute gestational diabetes.

Factors that may affect the result:

• deficiency of microelements (magnesium, potassium) in the body;
• disturbances in the functioning of the endocrine system;
• systemic diseases;
• stress and anxiety;
• simple physical activity (moving around the ward during the test);
• taking sugar-containing medications: cough medicines, vitamins, beta blockers, glucocorticosteroids, iron supplements, etc.

The appointment and interpretation of the analysis is carried out by a gynecologist, endocrinologist.

Preparation for GTT

To conduct a glucose tolerance test, venous blood is required, so the preparation rules for venipuncture are standard:

• blood is donated strictly on an empty stomach (break between meals is at least 10 hours);
• on the day of the test you can drink only plain water without carbonation, other drinks are prohibited;
• It is advisable to perform venipuncture in the morning (from 8.00 to 11.00);
• on the eve of the analysis, it is necessary to abandon drug and vitamin therapy, since certain drugs can distort the test result;
• the day before the procedure, it is advisable not to overwork yourself either physically or emotionally;
• It is prohibited to drink alcohol and smoke before the test.

Additional dietary requirements:

• 3 days before venipuncture, it is forbidden to follow diets, fasting days, water fasting or fasting, or change your diet;
• Also, 3 days before the test you must consume at least 150 grams. carbohydrates per day, while the last meal on the eve of venipuncture should contain at least 40-50 grams. carbohydrates.

Carrying out a test in pregnant women

The O’Sullivan method involves conducting a glucose tolerance test with a load in 3 stages.

Stage No. 1

30 minutes before the test, the patient must take a sitting/lying position and completely relax;

The health worker takes blood from the ulnar vein using venipuncture, after which the biomaterial is immediately sent to the laboratory.

The results of this step allow the doctor to diagnose probable gestational diabetes if the blood glucose level is above the normal value of 5.1 mmol/L. And “definite gestational diabetes” if the result is more than 7.0 mmol/l. If the test is not indicative or the results obtained are ambiguous, then proceed to the second stage of the test.

Stage No. 2

The body is given a special “load” in the form of a sugar solution (75 g of dry glucose per glass of warm water). Within 5 minutes, the patient should drink the liquid completely and remain in a sitting (lying) position for an hour. The sweetness of the drink can cause nausea, so you can dilute it a little with squeezed lemon juice. After 1 hour, a control blood sample is taken.

Stage No. 3

2 hours after taking the solution, another blood sample is taken. At this stage, the doctor confirms or denies the diagnosis of gestational diabetes.