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Key takeaways

• Gestational diabetes is high blood sugar that develops during pregnancy.
• It usually goes away after your baby is born.
• Screening is offered if you have certain risk factors.
• The main test is the oral glucose tolerance test (OGTT).

What is gestational diabetes?

Gestational diabetes is a type of diabetes that can only develop during pregnancy. It means your body has trouble managing sugar (glucose), leading to raised blood sugar levels.

This condition usually disappears after you give birth. It is most often caused by hormones produced during pregnancy, stopping insulin from working as it should.

Insulin is a hormone that helps to lower blood sugar. When insulin does not work well, your blood sugar level will rise. While gestational diabetes can pose some risks for you and your baby, it's reassuring to know that these can be lowered with early detection and good management.

Screening for gestational diabetes in the UK

Any pregnant person can develop gestational diabetes. However, some people are more likely to get it. Your care team will ask about risk factors at your booking appointment. You may be offered a test for gestational diabetes if one or more of these apply to you.

You are at higher risk if:

• You had gestational diabetes before – in a previous pregnancy.
• You had a large baby before – weighing 4.5 kg (about 10 pounds) or more.
• Your body mass index (BMI) is 30 or more – your midwife or doctor can help you work this out if you are not sure what it is.
• Family history of diabetes – you have a parent, brother, or sister with diabetes.
• Age 40 or over
• You are of South Asian, Black, African-Caribbean or Middle Eastern origin – even if you were born in the UK.
• Previous weight-loss surgery – you have had a gastric bypass or other weight-loss surgery.
• Polycystic Ovarian Syndrome (PCOS)

At each maternity check, a midwife will check a sample of your urine. If your urine contains glucose you may be offered testing for gestational diabetes.

If you have gestational diabetes, you will be offered more care during pregnancy and labour. It's important to manage the condition, as this helps to keep you and your baby as healthy as possible.For some, gestational diabetes can be improved by changes in diet and exercise. If these changes are not enough, medication may be offered.

The oral glucose tolerance test (OGTT)

To check for gestational diabetes, your care team will use a blood test that measures how your body handles sugar (the oral glucose tolerance test, or OGTT). This test is simple and does not harm you or your baby.

The OGTT takes just over two hours to complete. It is usually done at your antenatal clinic or hospital when you are 24-28 weeks gestation. In some cases it may be offered earlier.

How the OGTT is done

You will need to fast for 8-10 hours before the test. This means you should not eat or drink anything except water.

The test involves a few steps:

1. A health professional will take a blood sample to measure your fasting blood glucose level.
2. You will then be given a sugary glucose drink.
3. You will need to rest for two hours.
4. After two hours, you will have another blood test to check your sugar level again. This checks how your body is dealing with the glucose.

Your blood sugar level rises after you have the sugary drink. It should then return to normal as your body processes the sugar.

The results show how much sugar is in your blood (your plasma glucose level). This is measured in a unit called millimoles per litre (mmol/l). A higher number means higher blood sugar.

Interpreting the results

You will usually be diagnosed with gestational diabetes if either of these apply:

• Your fasting plasma glucose level is 5.6 mmol/l or more.
• Your 2-hour plasma glucose level is 7.8 mmol/l or more.

Next steps after a positive diagnosis

If you are diagnosed with gestational diabetes, you will receive extra care and support. You should be referred to a joint diabetes and antenatal clinic within one week. You should also be referred to a dietitian.

Your care team will explain what gestational diabetes means for you and your baby. You will receive advice and information on how to stay healthy. This includes how to check your blood glucose and what levels to aim for.

Managing gestational diabetes

Gestational diabetes can often be managed by making changes to your diet and exercise.You will be offered advice on these potential lifestyle adjustments. If these changes are not enough, you may require medication.

It is important to keep your blood sugar levels within an ideal range. This will be individualised for each pregnant person. This helps to keep you and your baby safe and healthy during your pregnancy.

Your care team may include:

• a doctor specialising in diabetes
• an obstetrician
• a specialist diabetes nurse
• a specialist diabetes midwife
• a dietitian
• your community midwife

You can expect to have more appointments, tests, and scans. You will be in touch with your diabetes and antenatal team every one to two weeks.

Diet and exercise

Eating a balanced diet which is lower in sugar can help manage gestational diabetes. Aim to eat plenty of fruit and vegetables, paired with protein rich foods. Choose foods with a low glycaemic index, which are foods that release sugar into your blood more slowly.

Regular, gentle exercise can also help lower your blood sugar levels. Walking for 30 minutes after a meal is one way to stay active. Pregnancy yoga, swimming, or aquanatal classes are also great options.

Monitoring your blood glucose levels

You will need to check your blood sugar levels throughout each day for the rest of your pregnancy. This helps you and your care team see if you are reaching your ideal blood sugar levels.

You will be given a kit to do this yourself. It involves pricking your finger and putting a drop of blood on a testing strip.

Your healthcare team will show you how to check your blood sugar level. They will tell you when and how often to check.

This is usually when you wake up (fasting) and one hour after each meal. If you are having two or more insulin injections, you might also check before meals and at bedtime.

Your blood sugar targets

Your care team will tell you what blood sugar levels to aim for. These are general guidance for most pregnant people, but they will vary for each individual:

• Fasting – below 5.3 mmol/l.
• 1 hour after meals – below 7.8 mmol/l.
• 2 hours after meals – below 6.4 mmol/l (if checking then).

You will be asked to keep a record of your blood sugar levels. Your healthcare team will review these results at your check-ups.

They will adjust your treatment if needed. With the right support, it is possible to have a healthy pregnancy and baby.