Gestational Diabetes: What It Is and How It Is Managed
Screening, diet, activity and follow-up for high blood sugar in pregnancy.
Before you use this guide: This is general educational information, not an individual medical assessment. We do not identify a clinician reviewer on this page, so please confirm personal health decisions with your doctor, midwife or paediatrician.
Gestational diabetes is high blood sugar that first appears during pregnancy. It is quite common, it can affect any pregnancy and it is not caused by eating too much sugar or by anything you did wrong. With the right care, most women with gestational diabetes have a healthy baby.
Why it happens
The placenta makes hormones that make your body less responsive to insulin. Most women's bodies make extra insulin to cope. In gestational diabetes, the pancreas cannot keep up, and sugar builds up in the blood.
Who is more at risk?
- A body mass index above 30
- Gestational diabetes in a previous pregnancy
- A previous baby who weighed more than about 4.5 kg (10 lb)
- A parent, brother or sister with diabetes
- A family origin with a higher risk, including South Asian, Black Caribbean and Middle Eastern backgrounds
- Polycystic ovary syndrome, or being older, especially over 35
Many women who develop gestational diabetes have none of these risk factors, which is why most women are screened.
How it is found
Most women are offered a screening test, often a glucose tolerance test, between about weeks 24 and 28. In some countries this is a one-step test, and in others a two-step test that starts with a quick glucose drink. If you have risk factors, such as a family history of diabetes or a previous large baby, your doctor may test you earlier or more than once. Gestational diabetes often has no symptoms, which is why testing matters. Thirst, frequent urination and tiredness are common in pregnancy and are not reliable signs.
Why managing it matters
When blood sugar stays high, extra sugar crosses the placenta and your baby may grow larger than usual. This can raise the chance of a difficult birth, caesarean birth, low blood sugar in the baby after birth, and pre-eclampsia. Keeping your blood sugar in range lowers these risks.
How it is managed
- Eating: have regular meals and snacks, and spread carbohydrates through the day. Choose wholegrains, beans, lentils, vegetables and fruit, and pair carbohydrates with protein. Sugary drinks, juice and sweets raise blood sugar fastest. Do not cut out carbohydrates completely. A dietitian can help you plan.
- Activity: a 10 to 15 minute walk after meals can lower blood sugar. See our guide to safe exercise in pregnancy.
- Monitoring: you may be asked to prick your finger and check blood sugar at home, often first thing in the morning and one or two hours after meals. Your team will give you targets, which vary a little between countries.
- Medicine: if diet and activity are not enough, you may be offered metformin tablets or insulin injections. Needing medicine does not mean you have done anything wrong, since the placenta's hormones are the cause.
- Extra care: you may have more frequent appointments and scans to watch your baby's growth and the amount of fluid around the baby.
Call your care team if your blood sugar readings are higher than your target for several days, if you feel very thirsty, vomit or feel unwell, or if your baby moves less than usual. If you take insulin or some other medicines and feel shaky, sweaty, confused or very hungry, your blood sugar may be too low. Take fast-acting sugar, such as glucose tablets or fruit juice, and recheck.
Labour and birth
- Your team will discuss the timing and way of giving birth. Many women with gestational diabetes can go into labour naturally, but induction or birth may be advised at or a little before the due date, particularly if you use insulin or your baby is large.
- Your blood sugar may be checked during labour.
- After birth, your baby's blood sugar is checked. Early, frequent feeds and skin-to-skin contact help.
After the birth
Blood sugar usually returns to normal after delivery, and medicines are usually stopped. But you have a higher chance of developing type 2 diabetes later, and your doctor will advise a follow-up blood test around 4 to 13 weeks after the birth, depending on your country, and regular checks every year after. Eating well, keeping active and staying at a healthy weight lower this risk, and breastfeeding may help too. If you plan another pregnancy, tell your doctor early, because you will usually be tested sooner.
Looking after your feelings
A diagnosis can feel worrying, and the diet and monitoring can feel like a lot. Many women feel guilty. It is not your fault, and it is manageable. Ask your team for a dietitian, a diabetes midwife or a support group, and tell them if you are finding it hard.
Where to check current advice
Testing and targets differ between countries and change over time. Check with your own health service, such as NICE and the NHS in the UK, the HSE in Ireland, ACOG and the American Diabetes Association in the US, Diabetes Canada and the SOGC in Canada, and Diabetes Australia and RANZCOG in Australia.
Trusted resources to read next
These public health resources provide additional information. Guidance can vary by country, so prioritise advice from your own care team and local health service.
- NHS: Pregnancy — Pregnancy care, common symptoms, screening and complications.
- NHS: Week-by-week pregnancy guide — Pregnancy development and care by week.
This content is for general information only and is not medical advice. Every pregnancy and every baby is different. Always talk to your doctor, midwife or paediatrician about your own situation, and seek urgent care if you are worried.