Published Mon, 2011-03-14 16:34; updated 4 years ago.

Diabetes is a condition in which the amount of sugar (glucose) in the blood is too high because your body can't store it properly.

Glucose comes from the digestion of starchy foods, such as bread and rice. Insulin, a hormone produced by your pancreas, helps glucose to enter the cells, where it's used as fuel for your body.

There are three types of diabetes that can affect you when you are pregnant:

Type 1 diabetes

This develops when your body can't produce any insulin. It usually begins in childhood, and most women with type 1 diabetes will be aware of their condition before they become pregnant. Type 1 diabetics take insulin to control their diabetes.

Type 2 diabetes

This develops when your body can't produce enough insulin, or when the insulin that is produced doesn't work properly. It often occurs in overweight people (80% of people with type 2 diabetes are overweight or obese), and is usually diagnosed in women aged 40 or more. But it can happen at a younger age, particularly in Asian and black people (at around 25 years old).

You may be aware that you have type 2 diabetes before you become pregnant, or you may be diagnosed during your pregnancy. Type 2 diabetes can be treated with tablets (and insulin, in some cases) to lower blood glucose. 

Gestational diabetes

This type of diabetes occurs only in pregnancy. It can occur at any stage of pregnancy, but is more common in the second half. It occurs when your body can't produce enough extra insulin to meet the demands of pregnancy. Gestational diabetes goes away after you've given birth.

You're twice as likely to develop type 2 diabetes later in life if you have gestational diabetes when you're pregnant.

Having diabetes when you're pregnant can put you and your baby at risk (see below). You can minimise these risks, but it partly depends on what type of diabetes you have.

Pre-existing diabetes

If you already have type 1 or type 2 diabetes, you may be at a higher risk of:  

  • Having a large baby, which increases the risk of a difficult delivery, having your labour induced, or a caesarean section. 
  • Having a miscarriage.
  • People with type 1 diabetes may have problems with their eyes, or a worsening of existing problems (called diabetic retinopathy) and their kidneys (diabetic nephropathy).

Your baby may be at risk of:

  • not developing normally and suffering from congenital abnormalities, particularly heart abnormalities.
  • being stillborn or dying soon after birth,
  • having health problems shortly after birth (such as heart and breathing problems) and needing hospital care, and
  • developing obesity and/or diabetes later in life.

The best way to reduce the risk to your own and your baby's health is to ensure that your diabetes is controlled before you become pregnant. Ask your GP or diabetologist for advice. You may be referred to a diabetic pre-conception clinic for support before you try to get pregnant.

You'll be offered a blood test called an HbA1c test, which helps to assess the level of glucose in your blood. It is best if the level is 6.1% before you get pregnant. If you score much higher than this (6.5%), get your blood glucose under better control before you conceive in order to reduce the risk of complications for you and your baby.

The normal daily dose of folic acid for women trying to get pregnant and for pregnant women is 400 micrograms. Diabetic women require a higher dose, of 5mg a day. Your doctor can prescribe high-dose folic acid for you. Taking folic acid helps to prevent your baby from developing birth defects, such as spina bifida.

Your diabetic treatment regime may remain the same during pregnancy, or your team may adjust it, depending on your needs. Some drugs that you're taking for conditions related to your diabetes, such as high blood pressure, may have to be altered.

It's very important to keep any appointments made for you, so that your care team can monitor your condition and react to any changes that could affect your own or your baby's wellbeing.

Your blood glucose level will be monitored more frequently, and your eyes and kidneys may be screened more often because eye and kidney problems can increase during pregnancy. You may also find that as you improve control over your diabetes, you suffer more hypoglycaemic (low blood sugar) attacks. These are harmless for your baby, but you and your partner need to know how to cope with them.

Gestational diabetes

You're more likely to develop gestational diabetes if:

  • you're overweight with a BMI (body mass index) above 30,
  • you've given birth to a large baby, weighing more than 4.5kg (9.9lbs), in the past,
  • you've had gestational diabetes before,
  • you have a parent, brother, sister or grandparent with diabetes, or
  • your origin is south Asian, black Caribbean or Middle Eastern. These ethnic groups have a higher risk of developing gestational diabetes.  

If you're in any of these higher risk categories, you'll be offered a test to check for gestational diabetes. You may be given a home testing kit to check your blood glucose levels, or offered an oral glucose tolerance test (OGTT or GTT) at 16-18 weeks and at 28 weeks (or earlier if you've had gestational diabetes in the past).

A GTT test is a blood test that's done after fasting. You'll be told how long not to eat for before the test (it's often overnight). You'll then be asked to drink a glucose drink and take another blood test two hours later.

If you're diagnosed with gestational diabetes it means you're at risk of: 

  • having a large baby, which increases the risk of a difficult delivery, having your labour induced, or a caesarean section.

Your baby may be at risk of: 

  • stillbirth,
  • health problems shortly after birth (such as heart and breathing problems) and needing hospital care, and
  • developing obesity and/or diabetes later in life.

Gestational diabetes can often be controlled by diet. A dietitian will advise you how to choose foods that will keep your blood sugar levels stable. You'll also be given a kit to test your blood glucose levels. If your blood sugar levels are unstable, or your baby is shown on an ultrasound scan to be large, you may have to take tablets or give yourself insulin injections.

Whatever type of diabetes you have, you will have more frequent, and sometimes time-consuming, antenatal appointments to check on the progress of you and your baby. You will be offered advice on diet and treatments to control your blood glucose levels.

Labour and birth

If you have diabetes, it's strongly recommended that you give birth with the support of a consultant-led maternity team in a hospital.

Babies born to diabetic mothers are often larger than normal. This is because blood glucose passes directly from you to your baby, so if you have high blood glucose levels your baby will produce extra insulin to compensate. This can lead to your baby storing more fat and tissue. This in turn can lead to birth difficulties, which require the expertise of a hospital team.

After the birth

Once your baby is born, their blood glucose level will be tested two to four hours after the birth using a heel prick blood test, to check whether it's too low. Feed your baby as soon as possible after the birth (within 30 minutes) to help keep your baby's blood glucose at a safe level (2mmol/litre).

If your baby's blood glucose level can't be kept at a safe level, he or she may need extra care. Your baby may be given a drip to increase their blood glucose.

When your pregnancy is over, you won't need as much insulin to control your blood glucose. You can decrease your insulin to your pre-pregnancy dose or, if you have type 2 diabetes, you can return to the tablets you were taking before you became pregnant.

If you had gestational diabetes you can stop all treatment after the birth. Your blood glucose levels will be checked before you go home, and again at your six-week check. You will also be given advice on diet and exercise.

NHS Choices