What Is Gestational Diabetes?
Screening, pregnancy management and postpartum care explained
Gestational Diabetes in Australia - Key Statistics
Of pregnancies affected
Weeks screening time
Future T2D risk
Resolves after birth
What is Gestational Diabetes?
Gestational diabetes mellitus (GDM) is diabetes that occurs during pregnancy. It develops because of pregnancy hormones (produced by the placenta), which stop insulin from working as usual (insulin resistance). If the pancreas cannot produce enough insulin to overcome this insulin resistance, blood sugar (glucose) accumulates in the blood stream and gestational diabetes develops1,2. The condition usually develops around the 24th to 28th week of pregnancy, but in some women it can occur earlier. For most women, diabetes normalises after the baby is born.
Gestational diabetes affects the way body cells use glucose. It causes high blood glucose that can affect the pregnancy and baby development. Whilst any pregnancy complication is concerning, gestational diabetes can be managed resulting in a safe pregnancy for mother and baby3.
Learning to manage diabetes will take time, but your health care team are there to support you.
Key Facts:
- • Affects 12-14% of pregnancies in Australia4
- • Usually develops in the second half of pregnancy5
- • Often has no obvious symptoms6
- • Usually resolves after birth, but increases future diabetes risk7
Risk Factors & Screening
Risk Factors
Screening Protocol
Early Screening - First Antenatal Visit
If one or more risk factors at first antenatal visit, test HbA1c.18
If HbA1c ≥ 6.0-6.4% OR previous gestational diabetes mellitus or local policy or individualised risk assessment, do an oral glucose tolerance test between 10 and 14 weeks.
Universal Screening - Week 24-28
Oral Glucose Tolerance Test (OGTT)17
OGTT Diagnostic Criteria
- • Fasting: ≥ 5.3-6.9 mmol/L OR19
- • 1 hour: ≥ 10.6 mmol/L OR19
- • 2 hour: ≥ 9.0-11.0 mmol/L19
*If HbA1c > 6.5% or if FPG ≥ 7.0 mmol/L or 2h PG ≥ 11.1 mmol/L this is Type 1 or Type 2 Diabetes in pregnancy.20
Management During Pregnancy
Treatment Goals
Fasting glucose (mmol/L)21
1-hour post-meal (mmol/L)21
2-hour post-meal (mmol/L)21
Blood Glucose Monitoring
Blood glucose monitoring helps to manage gestational diabetes. This is generally done using a glucose meter and a lancing device with lancets to measure the glucose. Blood glucose is generally monitored 4 times daily (fasting or 1-2 hours post main meals). Your health care team will inform you how often to measure and what glucose values to target.26
Eating Well
Eating well for diabetes involves choosing foods that provide nutrition for mother and baby and choosing the correct amount and type of carbohydrate across the day. A dietician can be very helpful in creating a meal plan.22,25
Exercise
Exercise can assist in keeping glucose values in the healthy range and can have additional benefits in pregnancy.
Medication
If blood glucose targets are not met with healthy eating and exercise, medication may be added. This is generally insulin. Metformin may be considered after discussion with your health care team.28,29,30
After Birth & Future Risk
Diabetes will usually resolve after the birth, however there is an increased risk of developing Type 2 Diabetes over time and it is important to have regular screening with your health care team.31,35
There is a much higher risk of gestational diabetes in subsequent pregnancies.36
Babies born to mothers with gestational diabetes have an increased risk of obesity and Type 2 Diabetes.
A healthy lifestyle can reduce the risk of these health outcomes.37,38,39
Need Specialised Care?
Connect with healthcare professionals experienced in gestational diabetes
References
1-3 Diabetes Australia. (2024). Gestational diabetes. Retrieved from https://www.diabetesaustralia.com.au/about-diabetes/gestational-diabetes/
4-7 Australian Institute of Health and Welfare. (2024). Diabetes: Australian facts, Gestational diabetes. Retrieved from https://www.aihw.gov.au/reports/diabetes/diabetes/contents/how-common-is-diabetes/gestational-diabetes
8-20 National Health and Medical Research Council. (2023). Clinical Practice Guidelines: Diabetes in Pregnancy. Retrieved from https://www.nhmrc.gov.au/about-us/publications/clinical-practice-guidelines-diabetes-pregnancy
21-30 Australian Diabetes in Pregnancy Society. (2024). ADIPS Consensus Guidelines for the Testing and Diagnosis of Gestational Diabetes Mellitus in Australia. Retrieved from https://www.adips.org/
31-41 Royal Australian and New Zealand College of Obstetricians and Gynaecologists. (2024). Diagnosis of Gestational Diabetes Mellitus. Retrieved from https://www.ranzcog.edu.au/statements-guidelines
Last reviewed: July 2026 · Next review due: July 2027
This website content is for informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or another qualified health provider with any questions you may have regarding a medical condition.