What is the Sullivan test?

The O’Sullivan Test is usually performed on pregnant women in order to determine if their body is doing good control of their glucose levels. In addition, it is internationally accepted as the most effective test for ruling out gestational diabetes, thanks to its affordable cost and benefits.

The prenatal doctor performs different pregnancy tests to control the health status of the pregnant woman and the fetus, among which is the pregnancy sugar test. This test is done to determine if a woman is adequately controlling her glucose levels when she is pregnant. It is performed as a routine examination for all pregnant women during the second trimester of pregnancy. Next, we will explain what it is and why it is so important.

The O’Sullivan Test: What is it?

This test consists of analyzing the blood of the pregnant woman, after ingesting a certain amount of glucose, in order to verify if her body is controlling blood sugar levels on its own. To carry out this test, the pregnant woman is given a solution of 50 g of glucose at a concentration of 25% in 200 cc. An hour is allowed to elapse and a blood sample is taken from it, through which the analysis of the sugar level is carried out.

In general, this pregnancy glucose test is performed when the woman is over 25 years of age and the pregnancy is between 24 and 28 weeks, because at this stage alterations in the proper functioning of the hormone called insulin usually appear. (produced by the pancreas), due to all the hormonal changes associated with pregnancy. But it is also appropriate in the following occasions:

If the woman has suffered from gestational diabetes in a previous pregnancy, this test is performed during the first trimester of pregnancy.

If there is a family history of diabetes (in this case, the test could be done both in the first three months and in the third trimester of pregnancy).

When the woman is over 35 years old.

In the event that the woman was overweight before becoming pregnant.

If in a previous pregnancy, the baby weighed more than 4 kilograms.

What are normal glucose levels in pregnancy?

Blood glucose values ​​considered normal during pregnancy are usually less than 140 mg/dL. Therefore, when performing the O’Sullivan test, the probable results are two: 

Positive: if blood glucose (7.8 mmol/l) is equal to or greater than 140 mg/dl.

Negative: if the referred level is below 140 mg/dL.

In the event that the result is positive, then there is a high probability that the woman suffers from gestational diabetes, so the next step is to carry out the gestational diabetes test, called the Oral Glucose Tolerance Test (OGTT), commonly called glucose curve, this being the most suitable test to detect gestational diabetes and verify its diagnosis.

what is gestational diabetes?

Insulin is a hormone produced by the pancreas and is responsible for generating glucose that must enter the cells of our body through the blood, so that it can be transformed into energy. When the woman is pregnant, the placenta produces high levels of hormones that prevent the proper functioning of insulin, which facilitates the elevation of blood sugar.

In this context, high glucose in pregnancy can be an indicator that the woman has gestational diabetes. This disease is a condition related to blood sugar values, which exceed normal levels. Gestational diabetes produces different effects during pregnancy, both for the mother and for the fetus. These are:

In the case of the mother: If this disease is controlled in time, the mother does not have to feel threatened and her delivery should be normal. However, if there is no timely control, the following could happen:

In some cases, the woman is likely to have an increase in her blood pressure or pre-eclampsia.

She is prone to gestational diabetes in subsequent pregnancies.

In the future, you are at risk of developing type II diabetes .

In the case of the fetus:

There may be complications in childbirth, related to the abnormal growth of the baby due to high basal glucose, making natural childbirth difficult and causing injuries to both the baby and the mother, making it necessary to perform a cesarean section, with the risks of this surgery.

The baby could have low blood glucose during the first few days after birth.

For the baby there are greater chances of death.

In general, gestational diabetes does not have any specific symptoms that are noticeable. You could probably have an increase in the frequency of urination or thirst, which would be an indication of this disease. So, if this is your case, we suggest you use the best wireless phone to request a medical appointment as soon as possible, so that the specialist is in charge of evaluating the possible risks of your condition and the plan to follow for your treatment.


On the other hand, if there is low glucose in pregnancy or hypoglycemia, the woman does not get enough energy that her body needs to perform all its functional activities, causing sudden fainting or dizziness, confusion, headache, hunger, anxiety, paleness, tachycardia, among others. The good thing is that this condition can be mild and is easily treated, it is enough to drink or eat some sweet or carbohydrate food so that your glucose level normalizes.

So, you know, if you’re on the sweet wait, it’s very likely that they’ll suggest you take the O’Sullivan test to determine your blood glucose levels. But you should not worry, because it is a simple test that does not generate major complications. In addition, it is the most internationally accepted method for ruling out gestational diabetes, for reasons of cost and benefit.

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