Gestational diabetes mellitus (GDM) is a type of diabetes that arises during pregnancy .Gestational diabetes typically affects pregnant women during the second or third trimester and is usually diagnosed by a blood test at 24–28 weeks into the pregnancy.

In some women, GDM occurs because the body cannot produce enough insulin to meet the extra needs of pregnancy. In other women, GDM may be found during the first trimester of pregnancy. In these women, the condition most likely existed before the pregnancy. 

Key points

Gestational diabetes (GDM) is diabetes that develops during pregnancy. Most women who have GDM have healthy pregnancies and healthy babies

You will be given advice about blood glucose monitoring, diet ,exercise and weight management to help treat the condition. You may be offered tablets or insulin injections. You will have further support in your pregnancy by a specialist healthcare team.

Occasionally GDM can lead to complications in pregnancy or birth, especially if it is unrecognised or is not well controlled.

GDM usually goes away after the baby is born but you have a higher chance of developing GDM in a future pregnancy and Type 2 diabetes later in life.

At the booking appointment you will be assessed for risk factors that can make you more likely to have gestational diabetes. These include:

  • Obesity 
  • A family history of diabetes (parent, brother or sister) 
  • An unexplained stillbirth or neonatal death in a previous pregnancy, and/or 
  • A very large infant in a previous pregnancy (4.5kg or over) 
  • You have had gestational diabetes before 
  • Your family origin is South Asian, Black Caribbean or Middle Eastern. 
  • Persistent sugar in your urine at Ante Natal visits. 
  • Excessive “water” around your baby. This is usually confirmed by a scan appointment. 
  • Diagnosed ‘large for dates’ diagnosed following USS.

If you have any of these characteristics you should be offered a test for gestational diabetes

If you are at risk of gestational diabetes you will be offered a glucose tolerance blood test at 28 weeks into your pregnancy. Women who have had gestational diabetes in a previous pregnancy will be tested at 16 weeks.

The test involves having a blood test taken in the morning when you've had nothing to eat or drink overnight. You're then given a glucose drink. After resting for two hours, another blood sample is taken to see how your body is dealing with the glucose.

Glucose tolerance blood tests are performed in our Maternity assessment unit on Tambootie ward and you will receive the results by phone the following day (hyperlink the patient information sheet). If the test is positive then you will be contacted by either a specialist midwife or diabetic nurse who will explain how this will affect your pregnancy.

Topics discussed are:

  • Foods to avoid
  • Healthy eating and exercise
  • Blood glucose monitoring and targets
  • What will happen during labour and after the baby is born
  • Feeding
  • Harvesting breastmilk

With good management of gestational diabetes, you can increase your chances of having a healthy pregnancy and baby.

  1. Being careful with carbohydrates

    All carbohydrates affect your blood glucose levels, so it’s important to be aware of the amount you eat. You may be advised to:

    • Eat less carbohydrates

    • Choose better types of carbohydrates

    • Spread your consumption of carbohydrates throughout the day

    • Try to choose nutritious carbohydrate-containing foods such as wholegrain starchy foods, pulses, fruit and vegetables

    • Limit your intake of highly processed carbohydrate foods, such as white bread, refined cereals and ready meals that have added fat, salt and sugar

    Go Low
    Carbohydrate foods that digest more slowly are often called “slow releasing carbs’. This means that they release glucose into the blood more gradually leading to lower blood glucose levels. Slow releasing foods are referred to as “low glycaemic index” or “low GI”. Choosing more low GI foods can help with keeping blood glucose levels down. Foods that tend to be lower GI are:

    • High in fibre

    • Wholegrains (non-refined)

    • Low in sugar

    • Whole foods rather than liquid e.g. whole fruit compared to fruit juices or smoothies.

    Including low GI foods in a meal will lower the GI of the entire meal. Since vegetables, salads and pulses tend to be high in fibre, including these in a balanced meal will lower the GI of the meal. Protein & Fats also lower GI but be careful of the calories! Low GI foods also keep you fuller for longer so can help with appetite control.

  2. Consuming less sugar

    It is important to reduce the amount of added sugar you have in your diet. You can do this by:

    • Reducing your intake of processed foods, especially sugary drinks, snacks and desserts

    • Reading food labels and choosing low/reduced-sugar versions of food and drink where possible

    • Reducing other types of sugar such as sucrose, glucose, dextrose, fructose, lactose, maltose, honey, invert sugar, syrup, corn sweetener and molasses

    • Using artificial sweeteners – some people worry about the safety of sweeteners, but you can talk through the different options with your healthcare team if you have any concerns

  3. Eat regularly
    Eat three regular meals a day – with or without healthy snacks – and avoiding long gaps in between. This will help you control your appetite and blood glucose levels.
  4. Perfect your portion sizes
    This will help you manage your blood glucose levels and prevent too much weight gain during pregnancy.
  5. Avoid ‘diabetic’ foods
    They offer no special health benefits, are expensive and may have a laxative effect.

Click this link or the image to see the Eatwell Guide.

eatwell guide poster.jpg

  • Your baby will stay with you unless they need extra care. You can usually have skin-to-skin contact with your baby straight away if you choose this. Occasionally they may need to be looked after in the neonatal unit if they are unwell or need extra support.
  • Your baby should have their blood glucose level tested a few hours after birth to make sure that it is not too low. 
  • Gestational diabetes usually goes away after birth and therefore you will be advised to stop taking all diabetes medications immediately after your baby is born. 
  • You should be offered a fasting blood glucose test 6 - 13 weeks after the birth of your baby at the G.P clinic. A small number of women continue to have high blood glucose levels and will be offered further tests for diabetes. 
  • You should be offered information about your lifestyle, including diet, exercise and watching your weight, to reduce your chance of type 2 diabetes in the future.
  • Up to 50% of women who have had gestational diabetes develop type 2 diabetes within the following 5 years. You will therefore be advsied to have a test for this every year.

Usually it does. Before you are discharged to the care of your GP you will be advised to have your bloods repeated 6 weeks following the delivery of your baby. This should be a fasting blood test six weeks after your baby is born and then it should be repeated every year by your GP. If you took medication (tablets or insulin) during your pregnancy, you will be able to stop them once your baby is born.

Women with GDM have a 30 per cent risk of developing Type 2 diabetes during their lifetime (compared to a ten per cent risk in the general population).

About five to ten per cent of women with GDM develop Type 1 diabetes sometime in their life. These women have a slowly developing form of Type 1 that is ‘unmasked’ during pregnancy. With this in mind will we advise you to continue with the “Healthy Eating Plan” that was adopted in pregnancy in order for you to have a healthy and happy future. You are more likely to develop GDM again if you have had it in previous pregnancies; but, if you are overweight and lose weight, you may cut your risk of having GDM again. If you plan another pregnancy you should be offered the opportunity to self-monitor your glucose levels, with an OGTT at 16-18 weeks which will be repeated at 28 weeks if normal.

Will I get GDM in other pregnancies?

You are more likely to develop GDM again if you have had it in previous pregnancies; but, if you are overweight and lose weight, you may cut your risk of having GDM again. If you plan another pregnancy you should be offered the opportunity to self-monitor your glucose levels, with an OGTT at 16-18 weeks which will be repeated at 28 weeks if normal.