Gestational diabetes and OGTT

Gestational diabetes is an increase in blood sugar levels that occurs during pregnancy and usually disappears after delivery. 

About 5% of pregnant women are affected by this condition.

What is gestational diabetes ?

Gestational diabetes is an increase in blood sugar levels that occurs during pregnancy and usually disappears after delivery.  

Screening for gestational diabetes is required for women who are at increased risk of developing the condition. It is carried out in the first trimester of pregnancy via a blood test with measurement of blood glucose when fasting and in the second trimester by an Oral Glucose Tolerance Test (OGTT). 

This condition is asymptomatic : there are no noticeable effects on the pregnant woman, and the only way to detect its occurrence is through laboratory testing.


OGTT by appointment

The purpose of the OGTT test is to monitor the reaction of the mother-to-be's body to the ingestion of a high-sugar solution. The test is performed in the laboratory after fasting for 10 to 12 hours. 

The screening process consists of four stages :

1. A first blood sample is taken when fasting.

2. This is followed by the ingestion of a highly sweetened drink containing 75g of glucose.

3. A second blood test is taken 1 hour after ingestion of the glucose solution.

4. A third and final blood test is taken 2 hours after ingestion of the glucose solution.

The screening is not very pleasant for pregnant women (very sweet drink).

PLEASE NOTE : The test lasts two hours, so make sure you bring something to do ! 


Do I need to be tested ? 

Screening does not take place routinely and should be carried out on women who are most at risk :  

_ Person with diabetes in their immediate family
_ Personal history of gestational diabetes in a previous pregnancy
_ Age (35 years and older)
_ Overweight

Screening may also be offered if you have previously had a large baby (macrosomia).

When and how does screening take place? 

_ Fasting blood glucose : in the first trimester or before pregnancy.

_ Oral glucose tolerance test (OGTT) : during the second trimester of pregnancy between 24 and 28 weeks.

What are the risks of gestational diabetes ?

For the mother : 
Increased risk of pre-eclampsia (high blood pressure in the mother associated with a high level of protein in the urine).

For the baby :
_ High birth weight (macrosomia), which can have consequences for the baby or the mother during delivery (caesarean section).
_ Risk of hypoglycaemia in the infant at birth.

Important to know : in “true” gestational diabetes, there are no malformations because the blood sugar disorder 
occurs after the baby’s organs have been formed. The risks are excessive weight gain (macrosomia) in the foetus with risk of trauma during delivery for the baby and caesarean delivery for the mother. 

What should I do in the event of a positive result ?  

In the event of a positive result, management including dietary measures, physical activity and monitoring blood sugar levels (blood glucose) can limit the complications associated with gestational diabetes.

If diabetes is undiagnosed or untreated, complications can arise :

At delivery :
In the majority of cases and if the diabetes is adequately controlled, the delivery will be normal.  
If the diabetes is poorly controlled, delivery may be induced before term. If the baby is large, a caesarean section will be offered.

After delivery :
Women who have had gestational diabetes have a higher risk of developing type 2 diabetes in the future. Blood glucose levels should therefore be checked after delivery to ensure they have returned to normal and then followed up every 1-3 years. 

To prevent the onset of diabetes, it is advisable to continue with dietary measures by maintaining a balanced diet and keeping physically active.

Ketterthill pregnancy booklet

Download the full Ketterthill pregnancy booklet and find all the details of your analyses during pregnancy !  

Do you want to carry out OGTT ? 

Make an appointment in one of our laboratories.
Ketterthill is a network of nearly 100 laboratories in Luxembourg