Gestational diabetes: what it means and how it's managed

Gestational diabetes (sometimes called GDM) is a type of diabetes that develops during pregnancy and usually goes away after the baby is born. It happens when your body can’t make enough insulin to meet the extra demands of pregnancy, so your blood glucose (sugar) levels rise. It’s common — affecting somewhere around 1 in 6 to 1 in 7 pregnancies in Australia — and if you’re diagnosed with it, please know it isn’t your fault and it isn’t caused by anything you did.

How it’s found. Gestational diabetes usually causes no symptoms, which is exactly why it’s screened for. In Australia you’ll typically be offered an oral glucose tolerance test (OGTT) between about 24 and 28 weeks. It involves fasting overnight, having your blood taken, drinking a sugary drink, and having your blood taken again once or twice over the following two hours. It’s not the most fun morning, so bring something to do and a snack for straight afterwards. Some people at higher risk are tested earlier as well.

What it means for you and your baby. Well-managed gestational diabetes usually leads to a healthy pregnancy and baby. Left unmanaged, higher blood glucose can lead to the baby growing larger than average (which can complicate the birth), and to other issues around delivery and in the newborn period — which is why keeping your levels in a healthy range matters. Your care team will keep a closer eye on you and your baby, often with some extra scans.

How it’s managed. The good news is that gestational diabetes is very well looked after in the Australian system, and for most people the main “treatment” is changes to diet and activity. You’ll usually be referred to a diabetes educator and a dietitian, who help you adjust what and when you eat — generally spreading carbohydrates across smaller meals and snacks — and you’ll likely be shown how to check your own blood glucose with a finger-prick monitor a few times a day. Gentle, regular activity (like a walk after meals) also helps your body use glucose. A smaller number of people need tablets or insulin to keep their levels in range, and if that’s you, it’s simply your body needing more support — not a failure of your efforts.

Looking after yourself. A diagnosis can feel overwhelming, especially with the monitoring and appointments layered on top of everything else. Be kind to yourself, lean on your diabetes team for the specifics (they’ve guided countless people through it), and take it one day at a time. Most people find they get the hang of the routine quite quickly.

After the birth. Gestational diabetes usually resolves once your baby is born, and your blood glucose is checked to confirm it’s settled. Because having had it raises your future risk of type 2 diabetes, you’ll be advised to have a follow-up glucose test around 6 to 12 weeks after birth and then regular checks in the years ahead — a good prompt to look after your long-term health, which staying active and eating well support.

Who’s more likely to get it? Some things raise the chance — being older, a higher body weight, a family history of type 2 diabetes, having had gestational diabetes or a large baby before, polycystic ovary syndrome, some medications, and certain ethnic backgrounds (including South Asian, Southeast Asian, Aboriginal and Torres Strait Islander, Pacific Islander and Middle Eastern). But plenty of people with none of these develop it, and plenty with several don’t — so a diagnosis genuinely isn’t a verdict on your lifestyle.

What does eating for it look like? Your dietitian will tailor it to you, but the general idea is steadier blood glucose rather than restriction: spreading carbohydrates across smaller, regular meals and snacks rather than large amounts at once, choosing higher-fibre, lower-GI carbs (wholegrains, legumes, most vegetables) over refined ones and sugary drinks, and pairing carbs with protein and healthy fats. You don’t go “no carb” — your baby needs energy — it’s about the type, amount and timing. Most people are surprised how manageable it becomes once they see their own readings respond.

Around the birth. With well-controlled gestational diabetes, many people go on to a normal birth. Your team will keep a closer eye on your baby’s growth, and may talk with you about timing, as some are advised not to go too far past their due date — the plan is individual. After the birth, your baby’s blood sugar may be checked in the first hours, as some babies dip low initially; early feeding and plenty of skin-to-skin help.

Your GP, midwife, diabetes educator and dietitian are your team here, and Diabetes Australia is a trusted Australian resource for information and support. With the right management, gestational diabetes is very much something you can handle — and most pregnancies go on beautifully.