Gestational diabetes test: how is it done?

The OGTT test can screen for gestational diabetes in the second trimester of pregnancy. Who does it concern and how does it unfold? We tell you everything so that you are best prepared for it.

During pregnancy, a pregnant woman can face some unforeseen circumstances. Especially in terms of health. Some future mothers can indeed develop complications and these nine months are then less easy to live with. Among the minor ailments of pregnancy, we find gestational diabetes.

Gestational diabetes can affect anyone. In some cases, this pathology is pre-existing, but not diagnosed. According to the WHO, it is a carbohydrate tolerance disorder leading to hyperglycemia of varying severity. Gestational diabetes usually develops in the second trimester of pregnancy. Today, it is possible to perform a screening test between 24 and 28 weeks. How is this test carried out? Who does it concern and what to do if it is positive? We take stock.

Gestational diabetes, what is it?

When you are pregnant, the body undergoes many upheavals, especially in terms of hormones. Insulin is a hormone naturally produced by the pancreas and which regulates blood sugar levels, or the level of glucose (sugar) in the blood. With the disruption of the hormonal system during pregnancy, it is possible to develop insulin resistance. Clearly, there is insufficient insulin production. Insulin thus struggles to regulate the level of glucose in the blood… and the glucose remains in the blood, causing hyperglycemia in pregnant women. In some more severe cases, gestational diabetes.

Read also: Gestational diabetes: risks and treatments

Gestational diabetes: how to detect it?

It should be noted that gestational diabetes is sometimes asymptomatic. However, some pregnant women may have symptoms such as:

  • Significant fatigue
  • Frequent and abundant urination (urine)
  • Increased thirst
  • Headaches (sometimes)


Screening for gestational diabetes is carried out between 24 and 28 weeks. It respects the recommendations of CNGOF (National College of Obstetrician Gynecologists). Women with risk factors will be automatically screened for:

  • History of gestational diabetes
  • History of fetal macrosomia (a heavy baby)
  • Family history of diabetes
  • History of glucose intolerance
  • Obesity and overweight
  • Age of pregnant woman (over 35)


Note that some maternity hospitals or some health professionals can also offer it to a pregnant woman, regardless of her state of health, if they wish.

In addition, during the first consultation of the monthly pregnancy monitoring, a test for sugar in the urine by urine test strip will be carried out (glycosuria). If sugar is present in the urine, a blood glucose measurement by blood test will be requested.

Carried out in a laboratory, this analysis makes it possible to measure the level of glucose in the blood.

Read also: Glycosuria and gestational diabetes: how to detect them and when to worry?

Gestational diabetes test: how is it done?

As explained above, gestational diabetes screening tests are performed in a laboratory. In the first trimester of pregnancy, the doctor may order the pregnant woman to measure fasting blood sugar.

Between 24 and 28 SA, it is the measurement of oral glucose levels during oral hyperglycemia (OGTT).

The principle is to administer to the pregnant woman 75g of sugar (standard amount of glucose). A blood test is first taken on an empty stomach. Then an hour later. Finally, a third blood test is taken three hours after ingestion of the sugar lump. A pregnant woman is not considered to have hyperglycaemia if these levels are:

  • Fasting blood sugar: normal less than 0.92 g / L
  • Blood sugar at one hour: normal less than 1.80 g / L
  • Blood glucose at two hours: normal less than 1.53 g / L

Gestational diabetes test: what if i have diabetes while pregnant?

If the results of the screening test show that you have gestational diabetes, the diagnosis should be discussed with your doctor. The latter will recommend that you follow a particular nutritional diet and therefore cut out certain foods that are too high in sugar. Be careful, this is mainly a food rebalancing and not a draconian diet! The idea is to control your weight gain by eating a balanced diet and small amounts at regular times. Also prefer starchy foods with a low glycemic index (lentils, chickpeas, brown rice, etc.). On the other hand, stay away from industrial cakes, sodas and pastries.

It is also important to continue to move throughout the week and to create a routine with a sports activity (suitable for pregnancy).

You will also need to self-monitor your blood sugar 4 to 6 times a day when you are pregnant to ensure that your blood sugar levels are acceptable.

If after 10 days, the blood sugar level has not returned and the hygienodietetic measures are not sufficient, treatment may be considered. These are rapid, subcutaneous insulin injections, either using an injection pen, syringe or insulin pump. Oral antidiabetics are contraindicated for pregnant women.

Namely that the medical follow-up of a future mother suffering from gestational diabetes is reinforced.

Gestational diabetes: what are the risks for mother and baby?

The biggest risk with gestational diabetes is macrosomia, which is giving birth to a big baby. This can lead to complications such as a cesarean section, premature delivery, or a torn perineum. The child is also at greater risk of overweight and obesity in the future. Concerning the mother, she also has a risk of preeclampsia or toxemia of pregnancy (associating high blood pressure, edema, rapid weight gain).

This is why it is necessary to screen for gestational diabetes and to be vigilant throughout pregnancy. Do not hesitate to ask your doctor and / or gynecologist for more information. You can also find it on the website of the French federation of diabetics.

Elise Poiret

Journalist specializing in parenthood, Elise writes for aufeminin and Parole de mamans. She is also very involved in the fight for women’s rights. If you only have to remember …