Quick answer. Gestational diabetes mellitus (GDM) is high blood glucose first detected in pregnancy. In Singapore, all pregnant women are offered a 75g oral glucose tolerance test (OGTT) at 24-28 weeks, done earlier if you have risk factors such as a BMI of 23 and above, family history of diabetes, previous GDM or a previous large baby. Most women control GDM with healthy eating, activity and home glucose monitoring; some need insulin. Good control reduces risks like an oversized baby (macrosomia), pre-eclampsia and birth complications. GDM usually resolves after delivery, but you need a repeat OGTT 6-12 weeks postnatally and lifelong follow-up, as about 1 in 3 women later develop type 2 diabetes. Care is shared with your obstetrician.
Managing diabetes, or worried about your blood-sugar control?
Message our care team on WhatsApp. Tell us what’s going on and we’ll help you find the right best endocrinology & diabetes clinic — free, with no obligation.
Chat with our care team on WhatsAppNot sure who to see? Find the right specialist →
In a medical emergency, or for severe or sudden symptoms such as breathing difficulty, chest pain, fainting or stroke signs, call 995 immediately.
Gestational diabetes mellitus (GDM) is one of the most common conditions in pregnancy, where blood glucose rises to abnormal levels because pregnancy hormones make the body more resistant to insulin. It does not mean you did anything wrong, and most women go on to have healthy babies, especially when GDM is picked up early and managed well.
In Singapore, screening with an oral glucose tolerance test (OGTT) is offered to all pregnant women as part of routine antenatal care, usually at 24-28 weeks. This guide explains who is at higher risk, how GDM is diagnosed, why control matters for you and your baby, how it is managed, and what postnatal follow-up looks like, including your future risk of type 2 diabetes. Your care will be shared between your endocrine or diabetes team and your obstetrician (O&G).
At a glance
| Aspect | What it involves | Why it matters |
|---|---|---|
| Screening test | 75g oral glucose tolerance test (OGTT) with fasting, 1-hour and 2-hour blood samples | Detects GDM that usually causes no symptoms |
| When | Routinely at 24-28 weeks; earlier if higher risk, then repeated if first test normal | GDM often develops in the second half of pregnancy |
| Higher risk | BMI 23 and above, family history of diabetes, previous GDM, previous large baby (over 4kg) | Guides earlier or repeat testing |
| First-line care | Healthy eating, physical activity, home glucose monitoring with a glucometer | Many women achieve good control without medication |
| If needed | Insulin (and sometimes oral medication), under specialist guidance | Brings glucose to target when diet alone is not enough |
| After delivery | Repeat OGTT at 6-12 weeks, then ongoing screening | About 1 in 3 women later develop type 2 diabetes |
Who is at higher risk of gestational diabetes?
Any pregnant woman can develop GDM, which is why screening is offered universally in Singapore. However, some factors raise your risk and may mean testing earlier in pregnancy:
- A BMI of 23 kg/m² and above (the threshold used for Asian populations)
- A family history of diabetes in a close relative
- Previous gestational diabetes in an earlier pregnancy
- A previous large baby (birth weight over about 4kg)
- Glucose found in the urine, or symptoms suggesting diabetes
- Older maternal age and certain ethnic backgrounds with higher diabetes risk
If you have these factors, your OGTT may be done early in pregnancy and repeated at 24-28 weeks if the first result is normal.
How is GDM screened and diagnosed (the OGTT)?
The standard test in Singapore is a 75g oral glucose tolerance test (OGTT). You fast overnight, then a fasting blood sample is taken. You drink a measured sweet glucose drink, and blood is taken again at 1 hour and 2 hours afterwards.
GDM is diagnosed if any one of these readings is at or above the threshold. Because GDM usually causes no symptoms, this blood test is the only reliable way to detect it. KK Women’s and Children’s Hospital (KKH) and Singapore General Hospital adopted universal screening using international (IADPSG) criteria, so the test is offered to all pregnant women rather than only those with risk factors.
Why GDM matters for mother and baby
Well-controlled GDM carries low risk, but persistently high glucose can affect both of you. Possible effects include:
- Macrosomia (an oversized baby), which can make delivery more difficult and raise the chance of a caesarean or birth injury
- Pre-eclampsia (high blood pressure in pregnancy)
- Polyhydramnios (excess amniotic fluid)
- Low blood sugar or breathing difficulty in the newborn shortly after birth
- A higher chance of childhood obesity and diabetes in the child later in life
The encouraging message is that good glucose control substantially lowers these risks, which is exactly why screening and management matter.
Managing GDM: diet, monitoring and insulin
Most women start with lifestyle measures, guided by a dietitian and diabetes nurse:
- Healthy eating: balanced meals, controlled carbohydrate portions, wholegrains, vegetables and lean protein, with limits on sugary drinks and refined carbohydrates
- Physical activity appropriate for pregnancy, such as walking after meals
- Home glucose monitoring with a glucometer, checking fasting and after-meal readings and recording them for your team
If glucose stays above target despite these measures, insulin is added; it is safe in pregnancy and does not cross to harm the baby. Some women are offered oral medication. Insulin needs often rise as pregnancy progresses and stop after delivery.
After delivery: postnatal follow-up and future type 2 risk
GDM usually resolves soon after your baby is born, and insulin (if used) is normally stopped. However, follow-up remains important:
- A repeat OGTT at 6-12 weeks postnatally to confirm your glucose has returned to normal
- Ongoing screening (often annually), because women who have had GDM have roughly a 1 in 3 chance of developing type 2 diabetes later in life
- Higher GDM risk in future pregnancies, so early testing next time
Maintaining a healthy weight, eating well, staying active and breastfeeding all help reduce your future diabetes risk. Your follow-up may continue with your GP, polyclinic or endocrinologist.
Related guides
- Best Endocrinology & Diabetes Clinics in Singapore — our editorial shortlist
- endocrinology & diabetes clinics directory
- Thyroid nodules & goitre
- Hyperthyroidism & Graves' disease
- Diabetic complications
Sources
- SingHealth – Gestational Diabetes Mellitus (GDM)
- KKH/SingHealth – Gestational Diabetes Mellitus: A Common Pregnancy Condition
- HealthXchange – Gestational Diabetes Mellitus: Test and Diagnosis
- NUH – Gestational Diabetes
Related conditions & guides
Related conditions and guides you may find useful:
- Confinement & Postnatal Recovery in Singapore
- Gynae & Well-Woman Health Screening in Singapore
- IVF Cost in Singapore
- Miscarriage in Singapore
- Morning Sickness in Pregnancy
- Postnatal Depression in Singapore
Part of our Diabetes & hormones guides · Browse all health topics