What is gestational diabetes?

Gestational diabetes mellitus is a type of diabetes that develops in some women during pregnancy because their bodies are not able to produce enough insulin to keep blood sugar (glucose) within an acceptable range. High blood sugar is usually found between the 24th and 28th weeks of pregnancy.

Gestational diabetes differs from other forms of diabetes in that it starts during pregnancy and usually goes away after the baby is born. The most common types of diabetes, type 1 and type 2, continue throughout life.

Gestational diabetes puts you at risk for developing high blood pressure during pregnancy. Your fetus could gain extra weight, complicating delivery. Women with gestational diabetes are at risk of having it again in future pregnancies, and they have an increased risk of developing type 2 diabetes, as early as five years after delivery.

What causes gestational diabetes?

As a fetus develops, the placenta produces several hormones. Some of these block the action of insulin, requiring your body to produce extra insulin. Gestational diabetes develops if your pancreas cannot produce enough extra insulin.

What are the symptoms of gestational diabetes?

Many women are surprised when they learn they have gestational diabetes because they have had no symptoms (increased thirst, increased urination, increased hunger, and blurred vision). However, diabetes symptoms may go unnoticed because increased urination and hunger are common during pregnancy. If symptoms of high blood sugar are noticed, it may indicate that diabetes was present before pregnancy.

How is gestational diabetes diagnosed?

Almost all women are tested for gestational diabetes between the 24th and 28th week of pregnancy; women with a high risk for the disease are tested earlier. Women who meet all the criteria for low risk do not have to be tested.

Two blood tests are done in a series to diagnose gestational diabetes. In the first (glucose challenge test), your blood is tested one hour after drinking 50 g (1.8 oz) of a sugary liquid.

If the result of that blood test is higher than expected, a three-hour oral glucose tolerance test is performed. After not eating or drinking (except water) for at least eight hours, you have a fasting blood glucose test to provide a baseline for comparing other glucose values. Then you drink 75 g (2.7 oz) to 100 g (3.5 oz) of the sweet liquid. Your blood glucose level is tested every hour for at least three hours. You have gestational diabetes if you have a high fasting glucose level or a high result on the three-hour test.

How is gestational diabetes treated?

Many women with gestational diabetes are able to keep their blood glucose levels within an acceptable range by eating a balanced diet that limits carbohydrates and by getting regular exercise. These measures may keep you from developing gestational diabetes in future pregnancies and prevent type 2 diabetes later in life.

If diet and exercise do not keep your blood sugar in an acceptable range, you will need insulin injections.

The goal of treatment is to reduce the risk of complications for you and your baby during pregnancy and after birth. If your blood sugar level and the fetus's weight are normal, you and your baby face no greater risk for complications than if you did not have gestational diabetes.

Click here for the St. Mary's Diabetes Management Center.

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