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A high level of glucose in the blood of a pregnant woman may have a negative effect not only on the body of the future mother, but also on the developing fetus. This sugar penetrates the placental barrier, stimulates the child’s pancreas to overproduce insulin, which in some respects works similarly to growth hormone (which is why children of mothers with diabetes often have a large birth weight – it is called fetal macrosomia).
There is also an increased risk that the fetus will be immature, there will be obstetric complications – more often there is a need to terminate pregnancy by caesarean section, perinatal injuries, polyhydramnios, and preeclampsia. After birth, babies often have low Apgar scores. There is also an increased risk of neural tube defects and heart defects in the newborn. This happens if glucose disturbances in a pregnant woman are not treated properly.
How to prevent it?
During pregnancy, a number of screening tests are performed to detect previously undiagnosed glucose metabolism disorders, including diabetes. If you are pregnant, your gynecologist will check your fasting blood glucose level during your first visit. Depending on the test result, the doctor may order you to repeat it (if blood glucose> 126 mg / dl) or refer you to another test – oral glucose loading test of 75 g (if blood glucose is in the 95-125 mg / dl range). But this is not the end. If your fasting blood glucose is <95 mg / dL (i.e. your glucose level is normal), your doctor will order a GCT (24 g oral glucose loading test) at week 28-50.
What is a pregnancy glucose test?
The Oral Glucose Load Test (GCT) is a test that checks how well your body metabolizes this sugar. The pancreas produces a hormone called insulin that allows the cells in your body to use glucose as fuel. If the pancreas cannot produce enough insulin, the blood glucose level rises.
GCT is the determination of the glucose level one hour after drinking a glass of water in which 50 g of glucose has been dissolved. The normal glucose level is <140 mg / dL one hour after glucose administration. If the result is 140–180 mg / dL, a 75 g glucose loading test must be performed. If the result of the latter test is normal, the 32 g glucose loading test should be repeated in the 75nd week of pregnancy, if not - your doctor will refer you to a diabetes clinic. There you will get all the necessary information on the use of a proper diet and medications.
How to prepare for the test?
You do not need to fasten before the 50 g glucose load test. You can visit the doctor or the laboratory where the blood will be collected at any time (the time of the last meal also does not matter). Typically, however, GCT is done in the morning along with other tests. Before that, you should buy 50 g of glucose in the pharmacy (the pharmacist will measure the right amount) and then, upon arrival at the doctor’s office or clinic, dissolve it in 150 ml of water (approx. 2/3 glass). In private clinics or clinics, you usually get a ready-made solution. The drink prepared in this way should be drunk quickly.
As you will have to wait at least 1 hour after consuming the glucose drink, make sure you don’t have any other appointments scheduled during this time. It is also worth taking something to read or an mp3 player with you to make the waiting time pass faster. After drinking this solution, nausea and dizziness may appear, so it is worth going with your partner or friend for such a test.
Eat rationally for the 3 days preceding the OGTT test. It is advisable to take 3 meals a day, between which you can have small snacks. The most important thing is that your diet contains about 150-200 g of carbohydrates. You will find them min. in: fruit, bread, cereals, pasta, rice, legumes (peas, corn, carrots).
Remember that the results of the glucose load test are reliable, you should be healthy (even a cold can falsify the GCT results).
What does the examination look like?
The test is based on the results of the glucose level in venous blood taken twice. This is the first time that you drink the solution. After that, you will be asked to drink a sweet drink containing glucose. It’s best to drink it as soon as possible. One hour after you have drunk this solution, the nurse will take a second blood sample from you and measure your glucose level. Under proper conditions, it is just 1 hour after a meal / drink intake that glycemia reaches its peak.
Remember! While waiting for the second blood sampling, you should not eat or drink anything (except still mineral water). After the second blood sampling, the test can be considered complete. Unless your doctor tells you otherwise, you can return to your daily activities, school, work and exercise. Don’t forget to eat and drink something.
How to interpret the results?
• fasting glucose <95 mg / dl and 1 hour after drinking a glucose solution <140 mg / dl - normal result;
• blood glucose after 1 hour 140 – 199 mg / dl – perform the stress test again, this time with 75 g of glucose;
• 1 hour glucose> 200 mg / dL and the result with a glucose load of 75 g is normal – at the 32nd week of pregnancy you will have to repeat the 75 g glucose load test.
What can affect the test results?
• stress (for the body it can be the result of surgery or a simple infection);
• performing too strenuous exercise;
• drugs: beta blockers (eg propranolol), steroids (eg prednisone), thiazide diuretics (eg hydrochlorothiazide), some drugs used to treat mental illness.
Before starting the examination, inform your doctor about all medications you are taking (both those prescribed by your doctor and those that are available without a prescription).
Text: lek. med. Matylda Mazur