Gestational Diabetes Mellitus

Diabetes in Pregnancy (Gestational Diabetes Mellitus)

In Australia about 5% of pregnant women are diagnosed with Gestational Diabetes Mellitus (GDM). It affects the pregnant woman, requiring dietary management or medication and can also affect the baby and the birth. It is an indicator that the woman may develop permanent diabetes later in life.

What is Gestational Diabetes Mellitus?

Gestational Diabetes is a condition where the blood glucose of a pregnant woman is raised above normal. During pregnancy your body is relatively resistant to Insulin. Insulin is a hormone in your body that lowers your blood glucose levels. If your body is not able to make enough Insulin to overcome this resistance, the glucose level will become elevated and you will develop Gestational Diabetes.

Diagnosis of Gestational Diabetes

To find out whether you have Gestational Diabetes you need a Glucose Tolerance Test (GTT).  It is performed approximately 6 months into the pregnancy (26-28 weeks gestation).

Women at high risk of Gestational Diabetes might be tested earlier in pregnancy. Some of the common risk factors include: a past history of Gestational Diabetes, family history of diabetes, being older than 30 years old, being overweight, previous complicated pregnancies, and belonging to a high-risk ethnic group (Asian (particularly Vietnamese), Indian, Mediterranean or Indigenous).

Treatment of Gestational Diabetes

The goal of Gestational Diabetes treatment is to avoid high glucose levels in the mother.

Gestational Diabetes is usually managed by home blood glucose monitoring and diet. Your diet should be rich in fruits and vegetables, foods that are low in saturated fat, including low fat dairy, and foods with a low glycaemic index (GI) such as grainy bread, low-GI cereals and basmati rice.

10-25% of women affected by Gestational Diabetes will also require Insulin injections. You are best managed by a team that might include an Obstetrician, Diabetes Educator and Endocrinologist (Diabetes Physician). More frequent antenatal visits and fetal monitoring might be required, especially if Insulin is used.

Effects of Gestational Diabetes on your baby and birth

If Gestational Diabetes is not managed effectively it can lead to fetal macrosomia (a large baby). Macrosomia can increase the risk of birth related complications such as shoulder dystocia (difficulty of the baby's shoulders passing through the pelvis), birth trauma of the infant (fractured bones or nerve injuries) and trauma to your pelvic tissues.

There is also an increased risk of an operative delivery (Forceps, Ventouse (Vacuum), Caesarean Section), as well as some early infant complications such as low blood glucose level.

If the glucose control is optimal and there are no other complications, vaginal birth at term is preferred. Blood glucose levels will be monitored in labour and during the first 24 hours after delivery. Infants will also have their blood glucose levels checked.

Long Term Effects of Gestational Diabetes

Women with Gestational Diabetes are at risk of developing permanent diabetes (Type 2) later in life. Testing with a Glucose Tolerance Test is recommended 6 weeks after pregnancy and 1-2 yearly thereafter. Women are advised to loose weight and maintain a healthy lifestyle to reduce their risk.

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