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Pre-existing diabetes and pregnancy

12-minute read

Key facts

  • Pre-existing type 1 or type 2 diabetes are different to gestational diabetes, in that you have the condition before the pregnancy, and it doesn’t go away when your baby is born.
  • Seeing your doctor while planning your pregnancy will give you the best chance of having a healthy pregnancy.
  • Keeping your blood sugar levels at or below target during your pregnancy will help minimise your risk of complications.
  • Your medicines and/or doses may need to change throughout your pregnancy.
  • A health team including your obstetrician, endocrinologist, midwife, diabetes educator and dietitian will work with you to keep you healthy during your pregnancy.

What is diabetes?

Diabetes is a condition where you have too much sugar (glucose) in your blood.

While high blood sugar levels are common to all types of diabetes, this happens for different reasons in different types of diabetes.

In type 1 diabetes, your body cannot make insulin. Insulin is a hormone that helps glucose move from your blood into your body’s cells. Lack of insulin causes glucose to stay in your bloodstream, causing high blood sugar levels.

In type 2 diabetes, your cells become less sensitive to the insulin made by your body, so glucose levels build up in your bloodstream. This is known as ‘insulin resistance’.

Gestational diabetes is a type of diabetes that develops during pregnancy, when pregnancy hormones make your body cells more insulin resistant. It usually stops being a problem after your baby is born, but your risk of developing type 2 diabetes after pregnancy stays high.

The information on this page is for people who have diabetes before becoming pregnant.

Pre-pregnancy health check

If you have type 1 or type 2 diabetes and are planning a pregnancy, it’s a good idea to visit your GP and diabetes team 3 to 6 months before you start trying to conceive. Managing your blood sugars before conception and throughout pregnancy gives you the best chance of having a healthy pregnancy and birth.

Your diabetes team can guide you on a range of topics to optimise your diabetes management and general health before trying to conceive.

Lifestyle-related things you can do may include:

Your doctor may also give you advice about medicines, including:

Your doctor may also perform some are examinations or refer you for tests, to make sure you are well, including:

How does pre-existing diabetes affect pregnancy?

Pregnancy can affect pre-existing diabetes in many different ways, making it more difficult to keep your blood sugar levels steady and within your target range.

Pregnancy may make your blood glucose levels more unstable. If you use insulin, your insulin doses may need to be adjusted more often than usual. If you have type 2 diabetes, you may need to have your medicines adjusted, and/or start to take insulin, even if you haven’t had to in the past. Your diabetes team may also adjust your blood glucose targets at diferent points in the pregnancy.

If you have type 1 diabetes and are taking insulin, your usual hypoglycaemia (‘hypo’) warning signs can change in pregnancy, so you may be more likely to suffer from hypos without realising. Your doctor or diabetes nurse may suggest you try continuous glucose monitoring. this means that you use a device that will alert you when your blood sugar level is dropping, without needing to rely on your warning signs. While hypos aren’t a risk to your baby they are important for your own safety and wellbeing.

If you have type 1 diabetes, you may also be at an increased risk of diabetic ketoacidosis (DKA) during pregnancy. DKA occurs when you don’t have enough insulin for your body to use glucose to make energy, and can be dangerous for you and your baby. DKA can happen to anyone with type 1 diabetes, but you are more likely to develolp it if you are unwell or have severe have morning sickness. Speak to your diabetes team about making a 'sick day plan’, so you know what to do if you get sick when you ar pregnant.

How is diabetes managed during pregnancy?

Your healthcare team

You will be cared for by a team of health professionals which may include:

  • an obstetrician who has experience with diabetes or high-risk pregnancies
  • a specialist endocrinologist, experienced in diabetes care during pregnancy
  • a diabetes educator to help you manage your diabetes
  • a dietitian who can provide dietary advice at all the different stages — before conception, during pregnancy and after the birth
  • a midwife who is experienced in all aspects of pregnancy and birth
  • your GP and pharmacist
  • a social worker or psychologist

Finding a health professional

Pregnancy, Birth and Baby's service finder helps you locate your nearest doctor, obstetrician, maternal child health nurse, and other health professionals across Australia.

FIND A HEALTH SERVICE — The Service Finder can help you find doctors, pharmacies, hospitals and other health services.

Blood sugar targets

While you may take good care of yourself already, pregnancy is a time when you need to take even more care. It is very important for your and your baby's health that your blood sugar levels are kept stable and within the target range your doctor sets for you.

Your doctor will discuss your individual target range. for most people, the recommended blood sugar levels are between 4.0 and 5.3 mmol/L when fasting (before meals), and 5.0 to 6.7 mmol/L 2 hours after a meal.

It is important that your blood sugar levels don’t drop significantly below these ranges (hypoglycaemia) while aiming for these targets. If you have frequent or severe hypoglycaemic episodes (hypos), your diabetes health team will most likely adjust your medicines and/or your blood sugar targets.

Medicines in pregnancy

Some medicines may need to be stopped or changed during pregnancy. Your doctor can guide you on which medicines need to be stopped or changed, and how to do this, before you become pregnant, or as soon as possible after you find out you are pregnant.

Even if your regular medicines are safe to take during pregnancy, the doses and maybe even types of medicine you need to control your blood sugar levels may change throughout your pregnancy. They might change often. Your doctors will guide you on how often to test your blood sugar levels and what medicines to use.

Some people with type 2 diabetes can control their blood sugars with diet and lifestyle measures before pregnancy or after birth, but may find that this needs to change during pregnancy. They may need to start medicines, including insulin, during pregnancy, for optimal blood sugar control.

It’s a good idea to check with your doctor before taking any medicine during pregnancy, whether it is prescribed, over-the-counter or herbal. If your doctor isn’t available, you can also ask a pharmacist — don’t forget to tell them that you have diabetes and that you’re pregnant.

If you notice your need for medicines changing significantly (for example, needing much less insulin than before), or your blood sugars becoming more unstable (for example, frequent hypoglycaemic episodes), contact your diabetes team for advice.

Possible complications for you or your baby

Diabetes that is not well-controlled during pregnancy can affect your long-term health and can also be risky for your baby.

There is a chance that some of the potential complications of diabetes, such as eye disease and kidney disease, may develop while you are pregnant. Your doctors can help monitor your risk of having these complications.

High blood sugar levels during pregnancy put you at a higher risk of pregnancy problems including:

These risks are reduced if you keep your blood sugars under good control.

How might pre-existing diabetes affect labour and birth?

Most people with diabetes can have a vaginal birth and will give birth to healthy babies.

If you have diabetes, it’s highly recommended to give birth in a hospital, so medical staff are available to help you if any complications occur. It’s a good idea to plan in advance where you’d like to birth your baby and who you’d like to be with you.

If your blood sugar levels have been high during your pregnancy, or your baby is expected to be large (over 4.5kg), your doctor may recommend certain interventions. These may include induction of labour before or on your expected due date or a caesarean birth. Your doctor will give you advice based on your specific circumstances.

During labour and birth, your blood sugar levels will be monitored closely by your medical team. You might have an intravenous drip with sugar and insulin while in labour, or the doses of your insulin will be adjusted by your medical team around your labour or caesarean section.

After birth, your baby will be monitored closely and have a heel-prick blood test every few hours for the first 1 to 2 days to check for low blood sugar levels. If your baby has low blood sugar, they may need extra feeds with expressed colostrum, expressed breastmilk, infant formula or glucose. If they continue to have low blood sugar level, they may also need an intravenous (IV) glucose drip and/or monitoring in the hospital’s special care nursery.

How might pre-existing diabetes affect breastfeeding?

Having diabetes won’t usually affect your ability to breastfeed, and breastfeeding can be helpful to both your and your baby’s health. Not all diabetes medicines can be safely used during breastfeeding, so check with your doctor whether you can continue to use the medicines you used while you were pregnant. Insulin is usually safe to use while breastfeeding.

Your doctor or midwife may recommend expressing colostrum in the late stages of your pregnancy. Any colostrum you express can be used for supplemental feeds, if your baby needs them, to treat of low blood sugar.

You can talk to your doctor, midwife or lactation consultant about any concerns about breastfeeding with diabetes. You can also call the Australian Breastfeeding Association on 1800 686 268 for breastfeeding support.

Resources and support

Diabetes Australia have detailed e-books about pregnancy with both type 1 and type 2 diabetes, as well as helpful information about planning for pregnancy with diabetes.

If you are pregnant or breastfeeding and would like to find out more about your medicines call Medicines Line on 1300 633 424 (Monday to Friday, 9am to 5pm AEST).

Videos about diabetes in pregnancy are available from Diabetes Australia in many languages.

More information is also available from the Pregnancy and Diabetes website of the National Diabetes Services Scheme.

You can contact the NDSS Helpline on 1800 637 700 for information and support.

Speak to a maternal child health nurse

Call Pregnancy, Birth and Baby to speak to a maternal child health nurse on 1800 882 436 or video call. Available 7am to midnight (AET), 7 days a week.

Learn more here about the development and quality assurance of healthdirect content.

Last reviewed: September 2023

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