high sugar in pregnancy

Overview

High sugar in pregnancy — often called gestational diabetes — is when your blood sugar (glucose) levels become higher than normal during pregnancy. It happens because the placenta produces hormones that can block the way your body uses insulin, the hormone that controls blood sugar. While sugar levels are often higher than usual, with the right care most people are able to manage them and have a healthy pregnancy and baby.

Yes, high sugar in pregnancy is a fairly common condition. In the UK, it affects around 1 in every 20 pregnant women, though some parts of the world see higher numbers.

It affects women and people who are pregnant — typically in the second half of pregnancy. You may be more likely to develop it if you are over 30, carry extra weight, have a family history of diabetes, or are of South Asian, Middle Eastern, or African-Caribbean background. It can happen to anyone, and often appears even when you have no obvious risk factors.

Symptoms

Common symptoms

• High sugar in pregnancy often doesn't cause any obvious symptoms. That's why it's usually found through routine testing.
• If symptoms do appear, they can include feeling thirstier than usual, needing to urinate more often, feeling unusually tired, or having a dry mouth.

Symptoms in children

• High sugar in pregnancy is a condition experienced by the pregnant person, not by children. However, if your baby's blood sugar drops after birth, a doctor or midwife will check and support them as needed.

Symptoms in older adults

• High sugar in pregnancy is not a condition in older adults, but having it puts you at higher risk of developing type 2 diabetes later in life. That's why your blood sugar is checked regularly after your pregnancy.

Causes

Main causes

• During pregnancy, the placenta makes hormones that help your baby grow, but these hormones can make it harder for your body to use insulin. This is called insulin resistance.
• Your body usually makes extra insulin to keep up, but if it can't produce enough, blood sugar levels rise.
• Heredity can also play a role: if your parents or siblings have diabetes, you may be more likely to develop high sugar during pregnancy.

Risk factors

• Being over the age of 30
• Having a body mass index (BMI) above 25, or being overweight
• Having a family history of type 2 diabetes
• Having had gestational diabetes in a previous pregnancy
• Being of South Asian, Middle Eastern, or African-Caribbean descent
• Having polycystic ovary syndrome (PCOS)
• Having previously given birth to a large baby (9 lb or more)

When to see a doctor

See a doctor urgently if:

• If you have symptoms of very high blood sugar, such as confusion, extreme weakness, or trouble breathing, get help immediately.
• If you notice reduced baby movement, new pain, heavy bleeding, or fluid leaking, call your maternity unit or emergency services as soon as possible.

Book a routine appointment if:

• You'll be offered a test for high sugar in pregnancy between 24 and 28 weeks. If you haven't booked this, ask your midwife or doctor.
• If you are concerned about any symptoms, or if you have questions about your care, talk to your midwife or doctor at your next appointment.

Diagnosis

High sugar in pregnancy is almost always picked up by a routine screening test, because it usually doesn't cause symptoms. You'll be offered an oral glucose tolerance test around 24–28 weeks.

Tests that may be done

• Oral glucose tolerance test (OGTT) — you fast overnight, have a blood test, then drink a sweet drink, and have another blood test two hours later.
• A blood sugar check may also be done earlier if you are pregnant and have risk factors.

What to expect at your appointment

You will be asked not to eat for 8–12 hours beforehand (only water is usually allowed, or black tea/coffee if advised). The test takes around 2 hours. If your results show high sugar, you'll be referred to a diabetes in pregnancy team or a specialist midwife.

Treatment

The goal of treatment is to keep your blood sugar within a healthy range to protect both you and your baby. You'll be supported by a maternity diabetes team who will check in regularly. Most people start with lifestyle changes, and only some need further support.

Self-care at home

• Have regular meals and snacks, and balance your plate with vegetables, protein, and wholegrain carbohydrates.
• Choose carbohydrate options with a low glycaemic index, like porridge, wholegrain bread, lentils, and pasta, and limit sugary drinks and sweets.
• Stay active with moderate exercise such as walking, swimming, or pregnancy yoga, if your midwife says it's safe.
• Check and record your blood sugar as often as your team advises, and keep a record to review together.

Medical treatments

If diet and activity are not enough to keep levels normal, your doctor may prescribe a glucose-lowering medicine or insulin injections. These are safe to use in pregnancy and are given based on your individual needs. Your team will show you how to manage them and adjust them as your pregnancy progresses.

When is surgery considered?

Surgery is not a treatment for high sugar in pregnancy. However, if your baby grows very large, your doctor may suggest a planned caesarean section, or induction, to reduce the chance of difficulties during birth.

Living with this condition

Living with high sugar in pregnancy means checking in with your blood sugar throughout the day, planning your meals and activity, and staying close to your maternity team. It can feel like a lot at first, but most people find a routine that works for them. Your care provider will guide you.

Lifestyle tips

• Try to walk after meals to help bring blood sugar down gently.
• Build regular snacks into your day so your sugar doesn't dip or spike.
• Stay hydrated with water, and avoid sweetened drinks.
• Talk about how you're feeling — pregnancy is a big change, and it’s okay to ask for emotional support.

Diet and exercise

Think of meals as a balance: half your plate non-starchy vegetables, a quarter protein (such as eggs, fish, beans, chicken), and a quarter carbohydrate (like wholegrain rice, bread, or potatoes). Choose proteins and fibre with each snack. If you were not active before, start slowly and build up. Always check with your midwife before beginning a new exercise routine.

Mental health and emotional wellbeing

It is completely normal to feel worried, anxious, or even angry when you hear you have high sugar in pregnancy. You may worry about your baby and your own health. These feelings can be intense. It's important to talk openly with your healthcare team, partner, or a counsellor. If you are struggling, seek support — you deserve it. Remember, this is a condition you are managing, not a personal failure.

Prevention

There is no guaranteed way to prevent high sugar in pregnancy, but you can lower your chance by maintaining a healthy weight before pregnancy, eating a balanced diet, staying active, and keeping your blood sugar in a normal range before conceiving. If you have had gestational diabetes before, talk to your doctor about steps you can take before your next pregnancy.

Vaccines

This condition is not related to vaccines, but staying up to date with recommended pregnancy vaccines can help keep you and your baby healthy. Ask your midwife or doctor about what is right for you.

Screening programmes

Screening is a routine part of pregnancy care. You should be offered a test for high sugar in pregnancy between 24 and 28 weeks. If you have risk factors, you may be tested earlier.

Complications

If left untreated

• If high sugar in pregnancy is not managed, it can lead to the baby growing too large (macrosomia), which may make vaginal birth more difficult and increase the chance of induction or caesarean birth.
• Your baby may have low blood sugar after birth, needing extra monitoring and feeding support.
• You have a higher risk of developing gestational hypertension or pre-eclampsia.
• There is a higher chance of developing type 2 diabetes later in life for you.

Long-term outlook

The outlook is very positive. With timely care, regular check-ups, and the right support, almost everyone with high sugar in pregnancy goes on to have a healthy baby. After giving birth, your blood sugar levels usually return to normal. You'll still be offered a check-up after 6 weeks to confirm this, and advice on how to reduce your long-term risk of type 2 diabetes. You are not alone — many people manage this condition well every day.

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