Tolerance test during pregnancy. Oral glucose tolerance test (OGTT). Causes of an increase in glucose levels

From the very beginning of the pregnancy period, significant changes in metabolic processes, including carbohydrate ones, occur in a woman's body. In order to identify violations of the latter, the determination of the level of sugar in the blood plasma and the oral glucose tolerance test during pregnancy are used. Compared with men, diabetes mellitus among women is much more common, and there is a clear association with the gestational period and childbirth - GDM (gestational diabetes mellitus).

Methods for detecting impaired carbohydrate metabolism

The prevalence of diabetes among pregnant women is on average 4.5% in Russia in their total number. In 2012, the Russian National Consensus defined GDM and recommended for practical application new criteria for its diagnosis, as well as treatment and postpartum care.

Diabetes mellitus in pregnancy is a disease characterized by high blood sugar, which is detected for the first time, but does not meet the criteria adopted for a newly diagnosed (manifest) disease. These criteria are:

• fasting sugar content is more than 7.0 mmol/l ( further in the text the same names of units of measurement) or equal to this value;
• A repeat-tested glycemia that is equal to or greater than 11.1 at any time during the day and regardless of diet.

In particular, if a woman's fasting venous plasma sugar level is less than 5.1, and in an oral glucose tolerance test 1 hour after exercise, less than 10.0, 2 hours later - less than 8.5, but more than 7.5 - these are normal variants 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?

Identification of carbohydrate metabolism disorders is carried out in stages:

1. Stage I examination is mandatory. It is prescribed at the first visit to a doctor of any profile by a woman for up to 24 weeks.
2. At stage II, an oral glucose tolerance test is carried out with 75 grams of glucose at 24-28 weeks of gestation (optimally 24-26 weeks). In certain cases (see below), such a study is possible up to 32 weeks; in the presence of high risk - from 16 weeks; when sugar is detected in urine tests - from 12 weeks.

Stage I consists in conducting a laboratory study of glucose in the blood plasma on an empty stomach after an 8-hour (not less) fasting. It is also possible to study the blood and regardless of the diet. If the norms are exceeded, but the blood glucose level is less than 11.1, then this is an indication for repeating the study on an empty stomach.

If the test results meet the criteria for newly diagnosed (manifest) diabetes, the woman is immediately referred to an endocrinologist for further monitoring and appropriate treatment. If the fasting glucose is above 5.1 but less than 7.0 mmol/l, GDM is diagnosed.

How to do a glucose tolerance test during pregnancy

Indications

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

1. Absence of deviations from the norm in the results of the first phase of the examination in the early stages of pregnancy.
2. The presence of at least one of the signs of a high risk of GDM, ultrasound signs of impaired carbohydrate metabolism in the fetus, or certain ultrasound dimensions of the fetus. In this case, the test is possible inclusively up to the 32nd week.

High risk signs include:

• high degree of obesity: body mass index is 30 kg/m 2 and above;
• the presence of diabetes in the closest (in the first generation) relatives;
• the presence in the past of gestational diabetes mellitus or any disorders of carbohydrate metabolism; in this case, testing is carried out at the first visit to the doctors (from 16 weeks).

Is the glucose tolerance test dangerous during pregnancy?

This study does not pose any risk to the woman and fetus until 32 weeks. 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;
• the presence of an acute infectious or acute inflammatory disease.

Preparation

Conditions for conducting a glucose tolerance test include:

1. Normal meals during the previous 3 (at least) days with a daily carbohydrate content of at least 150 g in the diet.
2. Mandatory content of carbohydrates in the amount of 30-50 g in the last meal.
3. Fasting (but not water restriction) for 8-14 night hours on the eve of testing.
4. Exclusion (if possible) of taking medicines containing sugar (pharmaceutical preparations of vitamins and iron, antitussives, etc.), as well as beta-blocking, beta-adrenomimetic and glucocorticosteroid drugs; they should be taken after blood sampling or inform the doctor about the need to take them before testing (for an adequate interpretation of the test results).
5. Warning the doctor about the test while taking progesterone.
6. Smoking cessation and sitting position of the patient until the end of testing.

Stages

They consist of:

1. Taking the first blood sample from a vein and analyzing it. In the event that the results indicate the presence of newly diagnosed or gestational diabetes mellitus, the study is terminated.
2. Carrying out a sugar load with normal results of the first stage. It consists in taking the patient 75 g of glucose powder dissolved in 0.25 liters of warm (37-40 ° C) water for 5 minutes.
3. Subsequent sampling and analysis of the next samples after 60 minutes, and then after 120 minutes. If the result of the second analysis indicates the presence of GDM, then the 3rd blood draw is canceled.

Interpreting the results of a glucose tolerance test during pregnancy

So, if on an empty stomach the concentration of glucose in the blood is less than 5.1 - this is the norm, above 7.0 - manifest diabetes; if it exceeds 5.1, but at the same time is below 7.0, or 60 minutes after the glucose load - 10.0, or 120 minutes after the load - 8.5 - this is GDM.

Tab. 1 Threshold values ​​of venous plasma glucose for the diagnosis of GDM

Tab. 2 Threshold values ​​of venous plasma glucose for the diagnosis of overt diabetes in pregnancy

The correct approach to the detection, as well as to the treatment of diabetes (if necessary) significantly reduces the risks of complications during pregnancy and childbirth itself and the risk of developing diabetes in the long term in women predisposed to it.

Pregnancy is both a pleasant and difficult time when the body is tested for strength. According to experts, approximately 4% of women after 16 weeks are faced with such a problem as gestational diabetes. It is noteworthy that this pathology can manifest itself in an absolutely healthy lady. To diagnose it, modern medicine suggests using the so-called glucose tolerance test during pregnancy.

What is gestational diabetes mellitus?

If you believe the doctors, then this problem can be dangerous not only for the woman herself, but also for the child in the womb. In diabetes, glucose, rather than insulin itself, enters the fetal bloodstream directly from the mother. As you know, the child's pancreas begins to form only in the second trimester. She immediately has to work hard to get a few mothers. The load on the child's gland as a result leads to the development of hyperinsulinemia. As a result, the baby is born with a low level of sugar, his breathing may be disturbed. As for the women themselves, who neglect timely treatment during pregnancy, they have problems with vision and kidney function.

Who is at risk?

The likelihood of developing gestational diabetes increases several times in the presence of the following factors:

• hereditary predisposition;
• excess body weight;
• disorders at the level of carbohydrate metabolism.

When is a glucose tolerance test prescribed during pregnancy?

The difficulty of diagnosing gestational diabetes mellitus lies in the fact that it practically does not manifest itself by any external signs, but at the same time, the sugar level rises, and its indicators decrease extremely slowly.

In this case, the most reliable method of diagnosis is the glucose tolerance test. Depending on its length, there are one-, two- and three-hour options.

Today, in almost all antenatal clinics, a glucose tolerance test during pregnancy is prescribed without fail. Experts recommend undergoing this study for a period of 28 weeks. However, if a woman is at risk, the analysis can be carried out earlier.

In addition, the test is required in the following cases:

• all women who have been diagnosed with diabetes in previous pregnancies;
• ladies with high (more than 30);
• women who gave birth to children weighing more than 4 kg;
• future women in labor with diseases of the endocrine system.

If the glucose tolerance test gave a positive result, the woman is monitored by doctors until the end of her pregnancy.

Preliminary preparation

First of all, it should be noted that the result of this analysis will be as informative as possible only if the woman takes into account all the recommendations described below.

The test is done only on an empty stomach and in the morning. On the eve of the evening, the future woman in labor is allowed a light dinner using sour-milk dishes. In the morning you can not smoke, drink alcohol, take any medications.

In addition, only absolutely healthy women are allowed to take a glucose tolerance test during pregnancy. If a woman has even a slight ailment, it is better to reschedule a visit to the doctor. Otherwise, the results may be somewhat distorted.

The cost of this study may vary slightly. So, in some medical institutions the final price varies from 750 to 900 rubles. The test result is usually known the very next day. The cost of the analysis includes the sampling of biomaterial, glucose itself and the study itself.

How is a glucose tolerance test performed?

How to submit it correctly? In fact, everything is very simple, you must strictly follow all the recommendations below.

The study itself, as a rule, is carried out in the morning and always on an empty stomach. Blood sampling is performed from a finger or from a vein. If on an empty stomach the sugar level does not exceed 6.7 mmol / l, the woman is given to drink glucose diluted in the most ordinary water. For an hour test, 50 g of glucose is diluted in 300 ml of liquid, for a two-hour test - 75 g, and for a three-hour test - 100 g. The result is very sweet water. To prevent the occurrence of vomiting, some ladies add a little citric acid to the solution.

Such a fairly simple procedure allows you to determine how the body reacts to the "sugar" load. That is why the simplest glucose tolerance test during pregnancy is used. shouldn't be much different. To be more precise, immediately after taking sweet water, glucose indicators increase, after an hour they decrease slightly, and after another 60 minutes they reach the initial parameters. If a repeat test shows that the glucose level is still at a fairly high level, we can talk about gestational diabetes.

After a few hours (the time depends on which glucose tolerance test was chosen), a second blood sample is taken. Until this time, the pregnant woman is recommended to be at rest. For example, you can lie down, read a book. Physical activity (even the most ordinary walk) forces the body to expend energy, which directly reduces performance. As a result, the result may be unreliable. In addition, during the analysis itself, it is necessary to stop smoking.

Interpretation of the results

If you were asked to take a glucose tolerance test during pregnancy, the results should normally be as follows:

• on an empty stomach - 5.1 mmol / l;
• 60 minutes after glucose load - 10.0 mmol/l;
• after 2 hours - up to 8.5 mmol / l;

If, according to the test results, the results do not meet the standard indicators, the doctor, as a rule, prescribes a second study. It takes place after a few days. Only after two positive results can a doctor make a final diagnosis. Based on only the first test, it is incorrect to talk about the presence of a problem, since the future woman in labor simply could violate the basic rules for preparing for the test. As a result, the examination shows a false positive result.

Contraindications

• early toxicosis.
• Diseases of an inflammatory or infectious nature.
• Exacerbation of chronic pancreatitis.
• The need for bed rest.
• The gestation period is more than 32 weeks.

Further tactics of pregnancy management

After the final confirmation of the diagnosis, the doctor prescribes treatment. During pregnancy, only insulin is allowed. Any categorically contraindicated. Scientists have proven that these medications can adversely affect the development of the fetus inside the womb.

In addition, a woman is recommended on an individual basis a special diet, which implies the exclusion of all easily digestible carbohydrates (chocolate, pastries, cakes, etc.). Only healthy, and most importantly, proper nutrition. It is equally important to constantly monitor the current. If the indicators are excessively high, it is recommended to call an ambulance.

It is important to note that gestational diabetes most often goes away without a trace immediately after childbirth. That is why doctors today prefer not to prescribe any specific treatment.

Conclusion

In conclusion, we note that the glucose tolerance test is a fairly informative method that allows you to confirm the presence of any disorders in carbohydrate metabolism, including in women in position. We hope that all the information presented in this article will be really useful for you.

The glucose tolerance test (TGT), also known as the oral glucose tolerance test (OGTT), tests the body's response to sugar (glucose). A glucose tolerance test is used to screen for diabetes. The most common glucose tolerance test is used to diagnose gestational diabetes, a type of diabetes that develops during pregnancy.

Why is a glucose tolerance test necessary?

The Oral Glucose Tolerance Test (OGTT), or glucose tolerance test, checks for carbohydrate metabolism disorders, that is, to check how well the body regulates sugar levels. This test detects the presence of diabetes or (GDM or gestational diabetes).

Gestational diabetes can develop even in women who are not at risk, since pregnancy itself is a significant risk factor for carbohydrate metabolism disorders.

Gestational diabetes usually has no noticeable symptoms, so it's important to get tested early so you don't miss the disease, as untreated GDM can have serious consequences for both mom and baby.

How is carbohydrate metabolism disorder diagnosed during pregnancy?

Stage 1. At the first visit of a pregnant woman to a doctor for up to 24 weeks, the glucose level is assessed. venous fasting plasma:

• result
• with fasting venous plasma glucose ≥ 5.1 mmol/L (92 mg/dL), but
• at the level of fasting venous plasma glucose ≥ 7.0 mmol / l (126 mg / dl), a preliminary diagnosis of overt (newly diagnosed) diabetes mellitus (DM) is established.

Stage 2. All women who did not have a violation of carbohydrate metabolism in early pregnancy undergo OGTT with 75 g of glucose between 24 and 28 weeks of pregnancy.

Do I need to prepare specifically for a glucose tolerance test?

Glucose tolerance test is performed on the background of a normal diet containing at least 150 g of carbohydrates per day for at least 3 days before the study. If you follow any diet, diabetes may simply not be detected, even if it is.

The test is performed in the morning on an empty stomach after an 8-14-hour overnight fast. Drinking water is not prohibited. Eliminate alcohol the day before the test. Smoking is prohibited until the completion of the test. If possible, before the end of the test, refrain from taking medications that affect blood glucose levels (multivitamins and iron supplements containing carbohydrates, glucocorticoids, beta-blockers, etc.).

Glucose tolerance test is not performed:

• with early toxicosis (nausea, vomiting);
• against the background of acute inflammatory or infectious diseases;
• with exacerbation of chronic pancreatitis or the presence of dumping syndrome;
• if it is necessary to comply with strict bed rest (the test can be carried out after the expansion of the motor regimen).

How is a glucose tolerance test performed?

During the entire test, you must sit. Physical activity (even walking) can affect the result of the study. For OGTT, a blood sample from a vein is used. The use of glucometers is prohibited.

Stage 1. A venous blood plasma sample is taken and the glucose level is measured. If the result is out of range, the test is terminated and a provisional diagnosis of diabetes or gestational diabetes (manifest diabetes) is made. If it is not possible to immediately determine the glucose level, the test continues and is completed.

Stage 2. After blood sampling, it is necessary to drink a glucose solution within 5 minutes, which consists of 75 g of dry glucose dissolved in 250-300 ml of warm water (when using glucose monohydrate, 82.5 g of the substance is needed). The start of taking a glucose solution is considered the beginning of the test. Glucose solution is a very sweet drink. For some, it can cause nausea or even vomiting. Do not try to drink a glucose solution in one gulp. To make the drink not so cloying, you can squeeze a little lemon juice into it.

Stage 3. 1 and 2 hours after the glucose load, the following samples of venous plasma are taken to determine the level of glucose (blood sampling is allowed only after 2 hours). If the result of a blood test taken after 1 hour can establish the fact of diabetes (gestational diabetes), the test is stopped.

In exceptional cases, OGTT with 75 g of glucose is possible up to 32 weeks of pregnancy.

If the test results indicate the presence of diabetes, the doctor may perform additional tests to confirm the diagnosis.

What blood glucose level indicates diabetes/gestational diabetes?

If the blood sugar level is very high, or if there are classic symptoms of high glucose levels in addition to a positive blood sugar test, then a doctor can diagnose diabetes on a single test. According to the American Diabetes Association, the following reference ranges for glucose should be used:

Threshold values ​​of venous plasma glucose for diagnosing diabetes:

Threshold values ​​of venous plasma glucose for diagnosis
gestational diabetes mellitus (GDM):

According to the results of OGTT with 75 g of glucose, it is enough to establish the diagnosis of gestational diabetes if at least one glucose level out of three is equal to or above the threshold. That is, if fasting glucose ≥ 5.1 mmol / l, glucose loading is not carried out; if at the second point (after 1 hour) glucose ≥ 10.0 mmol/l, then the test is stopped and the diagnosis of GDM is established.

If during pregnancy fasting glucose ≥ 7.0 mmol / l (126 mg / dl), or blood glucose ≥ 11.1 mmol / l (200 mg / dl), regardless of food intake and time of day, then they speak of the presence of manifest (newly diagnosed) diabetes mellitus.

Often, clinics conduct the so-called “breakfast test”: they ask the pregnant woman to donate blood (usually from a finger), then they send her to eat something sweet and ask her to come back after some time to donate blood again. With this approach, there can be no generally accepted threshold values, because everyone has different breakfasts, and it is impossible to exclude the presence of gestational diabetes based on the result obtained.

Is a glucose tolerance test dangerous?

A solution of 75 g of anhydrous glucose can be compared to a breakfast consisting of a donut with marmalade. That is, OGTT is a safe test for detecting carbohydrate metabolism disorders during pregnancy. Accordingly, the test cannot provoke diabetes mellitus.

Failure to test, on the other hand, can have serious consequences for both mother and child, as (pregnancy diabetes) will not be detected and appropriate measures will not be taken to normalize blood glucose levels.

Synonyms: glucose tolerance test, glucose tolerance test, GTT, oral glucose tolerance test, OGTT, test with 75 grams of glucose, glucose tolerance test, GTT, oral glucose tolerance test, OGTT.

Medical examinations and the delivery of various tests accompany a person all his life, but this is especially true for women during pregnancy, when it is necessary to monitor not one organism, but two at once. AND one of the required tests at the end of the second - the beginning of the third trimester (the optimal time for this test is 16-26 weeks) is a glucose tolerance test.

The fact is that even in a healthy woman who has never had diabetes, during this period a special latent type of illness may occur,. This is a dangerous phenomenon that harms not only the mother, but also the fetus, since it is not insulin that enters the bloodstream, but glucose, and the pancreas of the unborn child begins to work only closer to childbirth, and his body cannot cope with so many carbohydrates.

With this form of diabetes, preeclampsia can develop, which negatively affects the development of almost all the internal organs of the baby. It can also lead to asphyxia and death of the fetus in the womb. This disease is not common, but the possibility of severe complications and a huge number of risk factors make it necessary to conduct appropriate tests.

A glucose tolerance test detects the disease even when there are no symptoms characteristic of diabetes mellitus, and if it says that the blood sugar is increased, further examination is necessary. At risk pregnant women with increased weight, over 35 years old, women with a congenital predisposition to diabetes, impaired metabolism, heart and vascular diseases, as well as those whose previous pregnancies ended or gave birth to a dead child.

Contraindications for the test

Despite the importance of this test, there are a number of indications in which it not carried out at all or temporarily:

• diseases of the gastrointestinal tract, as a result of which there is no absorption of glucose;
• allergic reaction to glucose;
• early;
• late pregnancy;
• inflammatory and infectious diseases (until recovery).

Preparing for the test

There is nothing difficult in preparing for the test. 3 days before the delivery, the lifestyle should not change, but be habitual. Then comes the period of fasting, that is, from 8 to 14 hours only water is allowed to drink. Also, medicines are canceled per day, which can somehow affect the test result.

The test is carried out in the morning, since the woman did not take any food throughout the night. Blood is taken, most often from a vein, but possibly from a finger. Normal should not exceed 6.7 mmol/l. Then, if the indicator is normal, the woman is given a glucose solution. The amount of glucose depends on which test needs to be done - 1-hour or 2-hour. If the waiting time is 1 hour, then dilute 50 grams of glucose in 300 milliliters of water, 2 hours - 75 grams.

The solution is very sweet and for ease of drinking it is usually slightly diluted with citric acid. After taking water with glucose, the woman lies without unnecessary movements so that the body does not use energy and the results are not distorted. After the required time has passed, another blood sample is taken and the indicators are compared.

The norm of indicators of the test for glucose tolerance during pregnancy

• A normal fasting rate should not be more than 5.1 mmol / l.
• After a 1-hour test - 10.0 mmol / l.
• After two hours, the threshold is 8.5 mmol/l.

If the readings exceed the maximum allowable, then another test is performed a week later, and only after that it is possible to diagnose diabetes and begin its treatment. Treating a woman with suspected diabetes endocrinologist.