Gestational Diabetes Mellitus (GDM) in Singapore: Symptoms, Causes, and Management

Gestational diabetes mellitus (GDM), also known as pregnancy-induced diabetes, is a common condition in Singapore that affects 15–20% of pregnancies. This condition usually develops between 24 and 28 weeks of pregnancy due to changes in insulin sensitivity.

In this article, we cover what gestational diabetes is, its symptoms and causes, how it is tested, and the potential risks for mother and baby if unmanaged. We also cover practical strategies for managing blood sugar through diet, exercise, medication, and postpartum follow-up to ensure a healthy pregnancy and long-term well-being.

What is Gestational Diabetes Mellitus (GDM)?

Gestational diabetes refers to high blood sugar levels that develop during pregnancy. It occurs when the body is unable to produce enough insulin to manage the increased demands of pregnancy, leading to insulin resistance.

Insulin resistance is a normal physiological change during pregnancy. Hormones produced by the placenta help ensure that enough glucose is available for the developing baby. However, in some women, this process becomes excessive, meaning the body cannot effectively regulate blood sugar levels.

What Are The Symptoms of Gestational Diabetes Mellitus (GDM)?

Many women with gestational diabetes may not experience noticeable symptoms. This is why routine screening during pregnancy is important to detect the condition early.

When symptoms of high blood sugar occur, they may include:

Blurred vision
Excessive thirst
Fatigue
Frequent urination

As these symptoms can also occur during a normal pregnancy, testing is the most reliable way to determine whether gestational diabetes is present.

What Are The Causes of Gestational Diabetes Mellitus (GDM)?

Gestational diabetes develops primarily due to hormonal changes during pregnancy. Hormones produced by the placenta can reduce the effectiveness of insulin, the hormone responsible for regulating blood sugar levels. As pregnancy progresses, the body may struggle to produce enough insulin to overcome this resistance, resulting in elevated blood glucose levels.

Several factors may increase the risk of developing gestational diabetes, including:

Being a female over 35 or 40 years old
Personal history of any of the following:
- - Impaired glucose tolerance
  - HbA1C > 5.7%
  - Elevated fasting glucose
  - Previous gestational diabetes
Overweight or obesity at the start of pregnancy (BMI ≥ 25 – 27.5kg/m2 in Asian, BMI ≥ 30kg/m2 in Non-Asian)
Family history of diabetes
Medical conditions associated with the development of diabetes, e.g. Polycystic Ovary Syndrome (PCOS)
Those of South or East Asian, Native American, African, Hispanic, or Pacific Islander backgrounds
Previous delivery of a large baby, typically weighing more than 4kg

These factors do not guarantee that gestational diabetes will develop, but they can increase the likelihood and may prompt earlier screening.

How to Test for Gestational Diabetes Mellitus (GDM)?

Screening for gestational diabetes is typically performed between 24 and 28 weeks of pregnancy. Women with higher risk factors may be tested earlier in pregnancy. In Singapore, testing usually involves an Oral Glucose Tolerance Test (OGTT).

An OGTT is a two-step test used to screen and confirm gestational diabetes. This would typically require the patient to fast overnight, drink a glucose solution, and take blood samples at set intervals. Some individuals may experience mild side effects during these tests, such as nausea, lightheadedness, or dizziness, due to the sweet glucose drink or the fasting period. These effects are generally temporary.

There are other approaches to screening for gestational diabetes, such as the one-step approach or the three-hour oral glucose tolerance test. Your treating doctor will discuss with you which tests would be most appropriate for the level of risk that you have.

If you are due for diabetes testing or monitoring, consider arranging your glucose challenge test at LG Endocrinology, where you can receive professional support and accurate results.

What Is the Range for Suspected Gestational Diabetes?

If your glucose test results are higher than the recommended thresholds shown below, you may be diagnosed with gestational diabetes. Your doctor will typically review your results together with other aspects of your pregnancy health before confirming the diagnosis.

During screening, a 2-step OGTT is commonly used, in which blood glucose is measured 1 hour and 2 hours after the administration of 75g of glucose. According to the IADPSG and ADA criteria, a positive test for the diagnosis of gestational diabetes is made if any one of the values meets or exceeds the following levels:

Test Description	Plasma Glucose Level Criteria (mmol/L)	Plasma Glucose Level Criteria (mg/dL)
Fasting	≥ 5.1	≥ 92
1-hour post OGTT	≥ 10.0	≥ 180
2-hour post OGTT	≥ 8.5	≥ 153

How do I prepare for the Oral Glucose Tolerance Test (OGTT)?

Following a few simple guidelines before and during your OGTT can help ensure that your test results are accurate and reliable.

Schedule the test in the morning: The screening should begin early and is usually completed in the morning for accurate results.
Maintain your normal diet beforehand: Continue eating your usual balanced meals in the days leading up to the test. Sudden dieting or consuming unusually heavy meals may affect the reliability of the results.
Avoid strenuous physical activity: Do not engage in vigorous exercise before or during the test, as increased physical activity can influence blood sugar levels.
Fast for 8 to 10 hours before the test: Do not consume any food or beverages, except for small amounts of water.
Do not eat, drink, or smoke during the test: Once the OGTT begins, avoid consuming anything until the test is completed.

What Are The Risks of Unmanaged Gestational Diabetes Mellitus (GDM)?

When blood sugar levels are well controlled, most individuals with gestational diabetes can expect a healthy pregnancy and delivery. However, poorly managed or uncontrolled gestational diabetes may increase the risk of complications for both the mother and the baby. The possible complications associated with unmanaged gestational diabetes include:

Potential Risks for the Mother	Potential Risks for the Baby
Higher likelihood of caesarean section or induced labour if the baby grows too large for a safe vaginal delivery	Large birth weight (macrosomia), which may make delivery more difficult
Preeclampsia, a pregnancy complication characterised by high blood pressure	Birth injuries, such as shoulder dystocia, where the baby’s shoulder becomes stuck during delivery
Pregnancy-induced high blood pressure	Neonatal hypoglycaemia (low blood sugar) shortly after birth
Higher chance of premature delivery or medical induction of labour	Breathing difficulties or need for neonatal care after birth
Long-term risk of developing type 2 diabetes later in life	Higher risk of obesity or type 2 diabetes later in life
	Neonatal jaundice (yellowing of the skin and eyes)
	Stillbirth (rarely)

Concerned about gestational diabetes? If you have any questions or risk factors, book an appointment with Dr Linsey Gani at LG Endocrinology for personalised advice, testing, and management guidance.

How to Manage Gestational Diabetes Mellitus (GDM)

Managing gestational diabetes focuses on keeping blood sugar levels within a healthy range throughout pregnancy. This usually involves a combination of dietary changes, regular physical activity, monitoring blood sugar levels, and medical treatment when necessary.

Blood Sugar Management

Blood sugar management to achieve the glucose target is the key intervention for reducing the frequency and/or severity of complications related to GDM. Glucose targets are the recommended blood sugar ranges used to maintain optimal blood glucose levels and reduce complications.

Home monitoring: Glucose levels are checked before breakfast (i.e., fasting glucose level) and at one or two hours after the beginning of each meal using finger-stick glucose monitoring.

Glucose targets: Readings 20–30% above these ranges are considered suboptimal. Commonly used targets are as follows:

- - Fasting blood glucose: < 95 mg/dL (5.3 mmol/L)
  - One-hour postprandial blood glucose concentration: < 140 mg/dL (7.8 mmol/L)
  - Two-hour postprandial blood glucose concentration: <120 mg/dL (6.7 mmol/L)
Tracking and sharing: Keeping a record of blood sugar readings and sharing them with your healthcare provider helps determine how diet, activity, and medication affect glucose levels and allows for adjustments to your management plan if needed
Glucose sensor: Continuous glucose monitoring (CGM) using a wearable device is increasingly used by individuals who have difficulty performing regular finger-prick tests or prefer a more convenient, needle-free method that provides detailed, continuous information about their glucose levels.

Diet Management

A healthy, balanced diet is a key part of managing gestational diabetes. Choosing the right types of carbohydrates, proteins, and fats, along with proper food safety and hydration, can help keep blood sugar levels stable throughout pregnancy.

Balanced carbohydrate intake: Focus on complex, high-fibre carbs like whole grains, vegetables, and legumes, spread across three meals and 2–4 snacks to prevent blood sugar spikes.
Include protein in every meal: Protein slows glucose absorption and keeps you full; include lean meats, eggs, legumes, dairy, tofu, or nuts.
Add healthy fats: Healthy fats provide energy and support fetal growth; choose avocados, nuts, seeds, oily fish, and olive oil.
Limit sugary and processed foods: Avoid refined sugar, processed snacks, and sweetened drinks to prevent rapid blood sugar fluctuations.
Choose low glycaemic index (GI) foods: Low GI foods, such as oats, brown rice, and non-starchy vegetables, release glucose gradually and maintain stable blood sugar throughout the day.
Stay well hydrated: Drink plenty of water or sugar-free beverages to support overall health and hydration.
Follow safe food handling practices: Avoid raw or unpasteurised foods, separate raw and cooked items, and store/cook food properly to reduce the risk of foodborne illness.

Exercise

Regular physical activity can help improve the body’s ability to use insulin and regulate blood sugar levels. Healthcare guidelines generally recommend at least 150 minutes of moderate intensity exercise per week during pregnancy, unless advised otherwise by your doctor.

Safe examples of prenatal exercises include:

Brisk walking
Swimming
Prenatal yoga
Light strength or mobility exercises

However, physical activity should always be approved by a healthcare professional and introduced gradually, especially if you were not previously active before pregnancy.

Weight Management

Maintaining a healthy weight during pregnancy can help reduce the risk of complications associated with gestational diabetes. Excessive weight gain may increase the risk of high blood pressure, delivery complications, and larger birth weight babies. The recommended weight gain during pregnancy depends on the individual’s pre-pregnancy Body Mass Index (BMI).

Pre-Pregnancy BMI Category	BMI Range	Recommended Total Weight Gain
Underweight	< 18.5	12.5 – 18 kg
Healthy weight	18.5 – 24.9	11.5 – 16 kg
Overweight	25 – 29.9	7 – 11.5 kg
Obese	≥ 30	5 – 9 kg

Pharmacological Management

If dietary changes and exercise alone are insufficient, your doctor may recommend medication to help manage glucose levels.

In some cases, oral medications such as metformin may be prescribed. For individuals who require more intensive blood sugar control, insulin injections may be necessary during pregnancy.

Fetal Surveillance

Depending on your GDM control and risk, your obstetrician will decide on the monitoring regimen for the fetus. It is important to attend your appointments regularly with your obstetrician to ensure the health of your baby.

Regular Postpartum Follow-up

Gestational diabetes usually resolves after delivery, often within about 6 weeks after birth. However, individuals who have experienced gestational diabetes have a higher long-term risk of developing type 2 diabetes.

To monitor recovery, an OGTT is typically recommended 6 to 12 weeks after delivery to ensure blood sugar levels have returned to normal. In addition, annual diabetes screening for at least 5 years is usually advised.

Breastfeeding after childbirth may also help to manage gestational diabetes, as it can support postpartum weight management and improve long-term metabolic health for the mother.

FAQs About Gestational Diabetes Mellitus (GDM)

Do I need to be screened for gestational diabetes?

Yes, screening for gestational diabetes is important because it often has no obvious symptoms. Early detection through screening allows timely management, which helps reduce complications during pregnancy and delivery and protects the health of both mother and baby.

Why do I have gestational diabetes even though I’ve always been healthy?

Even if you eat healthily and exercise, it is still possible to develop gestational diabetes. During pregnancy, your body undergoes many changes to support your baby’s growth. In gestational diabetes, your body cannot fully adjust to these changes, such as managing insulin and blood sugar levels.

Factors like pregnancy hormones, insulin resistance, genetics, pre-existing health conditions, stress, and certain medications can all contribute. Maintaining healthy habits is still very important, as it helps manage gestational diabetes and supports your overall well-being throughout pregnancy.

How can gestational diabetes be prevented?

Gestational diabetes cannot always be prevented, but you can lower your risk by maintaining a healthy diet and staying physically active before and during pregnancy. Regular exercise and balanced, nutritious meals are the most effective steps.

How fast does gestational diabetes go away?

Blood sugar levels usually return to normal soon after childbirth as hormone levels stabilise. Your healthcare provider will typically test for gestational diabetes around 6 to 12 weeks postpartum to confirm that it has resolved.

Keep in mind that about 50% of individuals with gestational diabetes may develop Type 2 diabetes later in life. Eating a balanced diet, staying active, and following periodic blood glucose checks can help reduce this risk.

Does drinking water help control blood sugar in gestational diabetes?

Drinking water won’t directly lower blood sugar, but staying hydrated supports blood sugar regulation. Water helps your kidneys remove excess sugar and improves how your body uses insulin.

Can gestational diabetes be reversed during pregnancy?

Gestational diabetes cannot be reversed during pregnancy. Management focuses on controlling blood sugar through diet, exercise, and medication if needed. Your healthcare provider will check for diabetes after delivery, usually 6 to 12 weeks postpartum.

How concerned should I be about gestational diabetes?

Gestational diabetes is common, and with the right care, most individuals have a healthy pregnancy and baby. At LG Endocrinology, we provide guidance on diet, safe exercise, and, if needed, medication, helping you manage blood sugar levels throughout your pregnancy.

We’re here to support you every step of the way. If your readings are consistently high or you have any concerns, Dr Linsey will work with you to adjust your care plan and ensure both you and your baby stay healthy. If you’d like personalised guidance and ongoing support, book an appointment with LG Endocrinology to create a plan tailored to your needs today.

Disclaimer
This information is provided for general education. It does not replace personalised medical advice. Please consult your doctor for guidance on the medications that may be appropriate for you.

¹Retrieved from SingHealth HealthXchange.sg

Dr Linsey Gani is an endocrinologist experienced in conditions related to hormonal imbalances, including those affecting fertility, menstrual health, and reproductive function. Dr Gani completed her residency in Melbourne, Australia. She is a fellow of the Royal Australian College of physician and the Academy of Medicine, Singapore.