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Diabetes in pregnancy

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You may already have diabetes or develop gestational diabetes during pregnancy. This means you will need to be referred to the specialist diabetes team at the hospital. You can continue to receive care from your midwife, LMC or general practice team in the community as well.

Gestational diabetes

Hormones made in the placenta during late pregnancy make it harder to control blood glucose (sugar) levels.

Some women cannot make enough insulin to keep up with these changes. This causes their glucose levels to rise, causing gestational diabetes.

When the mother's glucose levels rise, so does the baby's, which can make it produce too much insulin. This can make the pēpi (baby) grow too much and has other harmful effects.

You are more at risk of getting gestational diabetes if you:

are overweight
have a family history of diabetes
have polycystic ovary syndrome
have had gestational diabetes before
have prediabetes (impaired glucose tolerance)
are from certain ethnic groups, such as Māori, Pacific peoples, Chinese, Indian and South-East Asian.

Gestation diabetes is usually temporary and goes away after your pēpi is born. But you have a higher risk of getting Type 2 diabetes in the future so you should have a diabetes test every year.

Diabetes New Zealand has more information on gestational diabetes.

Testing for gestational diabetes

All pregnant women are offered an antenatal blood test early in their pregnancy. This includes the HbA1c test, which screens for diabetes.

Between 24 and 28 weeks of pregnancy, you will be offered a screening blood test called the polycose test. For this test, they will give you a drink containing glucose. They will then take a sample of your blood 1 to 2 hours later. If the test is high, you will need to have a second test, called the glucose tolerance test.

If you have any of the risk factors above, you will be offered the glucose tolerance test straight away. You will not need to have the polycose test first.

If your lead maternity carer thinks you might be getting diabetes after 28 weeks, they may screen you again later in your pregnancy.

Treating gestational diabetes

You can usually manage gestational diabetes with healthy eating and regular physical activity.

Some people might need metformin tablets or insulin injections.

For more information about managing gestational diabetes, see Online education for diabetes in pregnancy. The page includes videos with advice about eating well to manage gestational diabetes and about testing blood glucose levels.

Type 1 diabetes

If you have type 1 diabetes, you will be taking insulin to control your blood glucose levels. It is important to have good control of your glucose levels before becoming pregnant. This is to avoid unnecessary complications. Insulin is safe in pregnancy, and you should keep using it.

If possible, see your general practice team or diabetes specialist in the months before you plan to become pregnant. You should also take a higher dose of folic acid than women without diabetes (5 mg daily). You will need a prescription from your doctor for this.

Type 2 diabetes

If you have type 2 diabetes, you may be taking medication to control your blood glucose levels. It is important to have good control of your glucose levels before becoming pregnant. This is to avoid unnecessary complications.

If possible, see your general practice team or diabetes specialist in the months before you plan to become pregnant. This is so they can make any necessary adjustments to your medication.

If you become pregnant unexpectedly, do not stop your medication. Make an appointment to see your general practice team as soon as possible.

Try to maintain a healthy weight both before and during your pregnancy. You should also take a higher dose of folic acid than women without diabetes (5 mg daily). You will need a prescription from your doctor for this.

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