Oral glucose load (OGTT)

According to the new Guidelines for the screening and diagnosis of gestational diabetes of The HAPO Study Cooperative Research Group, the two-step procedure (“carbohydrate miniload” + OGTT in cases with positive miniload) previously used is to be considered outdated and therefore is not recommended. Here are their prescriptions.

When and how to take the oral glucose load test (OGTT)

Regardless of the presence of any risk factors for gestational diabetes, between 24 and 28 weeks of gestation all pregnant women must take oral glucose load tests (OGTT – Oral Glucose Tolerance Test).

Even those who – fasting – during the first visit made during pregnancy had a blood glucose lower than 92 mg / dl. The same for those who had no previous diagnosis of overt diabetes.

This is because the screening, diagnosis and treatment of gestational diabetes are cost-effective.

The methods of performing the oral load test with 75 g of glucose (OGTT) can be summarized as follows:

  1. During the test the woman must remain seated or lying down without smoking or eating.
  2. This test is usually done in the morning after a fast of at least 8/12 hours.
  3. The woman should eat normally in the days preceding the test (taking at least 150 g of carbohydrates per day);
  4. In the days preceding the test, the woman must do normal physical activity.
  5. For the determination of plasma blood glucose, the OGTT should be performed by taking 75 grams of glucose and with venous samples at 0′, 60′ and 120′ times (i.e., before taking the glucose solution, one hour after, two hours after).

For the diagnosis of gestational diabetes with OGT 75 g it is sufficient that, beyond the established limit, it is only one of the three maximum glucose reference values – indicated in the table below.

The results of the oral glucose load test are given in milligrams per deciliter (mg/dL) or millimoles per liter (mmol/L).

Plasma glycemia Mg/dl   Mmol/l
fasting:    92    5,1
after 1 hour:    180    10,0
after 2 hours:    153     8,5

Diabetic women as well as those with gestational diabetes should be monitored during pregnancy by a multidisciplinary team with different professional figures.

The postpartum control test

After 8-12 weeks after delivery, the glucose tolerance of women with gestational diabetes should be reconsidered by means of an oral glucose load OGTT 75 gr.

The methods of execution of the test and the interpretative criteria are the same as those used for non-pregnant subjects.

Diabetes in gestation generally disappears shortly after delivery, while during pregnancy it is possible to control it according to what will be advised to them with some simple measures that allow them to follow a healthy lifestyle.

Katherine Johnson, M.D., is a board-certified obstetrician-gynecologist with clinical expertise in general obstetrics and gynecology, family planning, women’s health, and gynecology.

She is affiliated with the Obstetrics and Gynecology division at an undisclosed healthcare institution and the online platform, Maternicity.com.

Leave a Reply

Your email address will not be published. Required fields are marked *