What is gestational diabetes mellitus, why do women get it and how common is it?

In Singapore, about 8% of all pregnancies are complicated by gestational diabetes mellitus.

If you have never had diabetes mellitus before but have high blood glucose levels during pregnancy, you are said to have gestational diabetes mellitus.

“During pregnancy, your placenta produces hormones that block the action of insulin, a hormone that is important for controlling blood glucose. This results in an increased insulin requirement during pregnancy,” says Dr Lim Wei Ying​, Associate Consultant, Department of Endocrinology, Singapore General Hospital, a member of the SingHealth​ group.

Gestational diabetes mellitus occurs because your body is unable​​ to produce enough insulin during pregnancy, resulting in high blood glucose levels. Gestational diabetes mellitus usually starts in the second or third trimester of pregnancy.

Risk factors of gestational diabetes mellitus

You are at a higher risk of gestational diabetes mellitus​ if you have:

1. Body mass index (BMI) of 25 and above (or 25kg/m2)
2. First degree relatives (parents, siblings or children) with diabetes mellitus
3. Personal history of previous gestational diabetes mellitus, or large babies weighing over 4kg
4. Previous poor pregnancy (obstetric) outcomes that are usually associated with diabetes mellitus.

How does gestational diabetes mellitus affect you and your baby?

Although most women with gestational diabetes mellitus have healthy pregnancies and babies, gestational diabetes mellitus may occasionally cause serious problems.

When your blood glucose is too high during pregnancy, your baby will produce more insulin which can make him grow bigger.

This results in a higher likelihood of:

1. the need for induction of labour,
2. the need for caesarean section,
3. serious birth problems
4. stillbirth.

Your baby is also at a higher risk of

• ​having low blood glucose levels after delivery, and
• is more likely to require additional care in high dependency or intensive care units (ICU).

In addition, mothers with gestational diabetes mellitus are more likely to have:

1. high blood pressure,
2. preeclampsia,
3. miscarriages, and
4. bleeding problems post-delivery.

Babies of mothers with gestational diabetes mellitus are more likely to have:

1. jaundice,
2. birth trauma,
3. premature birth and
4. respiratory difficulties.

It is therefore important to diagnose and treat gestational diabetes mellitus optimally to reduce these risks.

See the next page to discover the​ diagnosis, treatment options​ and​ risks of diabetes after pregnancy​.​

Ref: O17