Gestational Diabetes mellitus

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What is gestational diabetes mellitus?

Gestational diabetes mellitus (GDM) is a form of diabetes which affects up to 15% of women in pregnancy. It occurs as the body is not able to produce enough insulin (a hormone from the pancreas) to bring down blood sugar (glucose) to normal levels. It results in your blood having very high blood sugars which can then cross to your baby.

Who is at risk?

One in six women can develop gestational diabetes in pregnancy. Risk factors include:

  • Women who are overweight (BMI > 30)
  • Women with a family history of diabetes (eg parents)
  • Woman from certain ethnic minority backgrounds

GDM usually develops after 24 weeks, and so if you have a risk factors, your midwife will arrange a glucose tolerance test for you. This will show whether you have developed diabetes during the pregnancy.

Most women do not feel unwell with GDM and often do not have any symptoms. Even if you have no risk factors, if glucose is present in your urine, or your baby is larger than expected or have too much water around your baby, you midwife will arrange a test for you.

Management of gestational diabetes

If you are found to have GDM you will be contacted by the Diabetes Midwives and taught how to test your own blood glucose (sugar) at home 4 times a day. This is a simple and relatively painless procedure and allows us to see what happens to your blood glucose on a daily basis. There are some information videos you may find useful here.

Many women can control their blood sugar by adjusting their diet and taking more exercise. You will be offered dietary support and will also be in regular contact with the Diabetes Midwives. It is important to avoid sugary and processed/refined foods like cakes, biscuits and soft drinks, and reduce foods made from white flour. Try to balance your meals by pairing slow release wholegrain carbohydrates with healthy fats, protein and lots of vegetables/salad (see diet sheet).

If your blood glucose levels are still raised after changing your diet and lifestyle, you will be offered treatment to control them. This could either be tablets (called Metformin) or insulin, or a mixture of both.

You will be offered extra care in the Joint Obstetric/Medical Clinic which is held in the Antenatal Clinic (ANC) where you may be seen by both the pregnancy and medical doctors. You will be offered extra scans to monitor the baby’s growth and a decision may be made to induce your labour early (normally between 38 and 40 weeks).

How does it affect my baby?

Raised blood glucose levels can affect your baby’s growth leading to a condition called “macrosomia”. Some babies develop extra fluid around them called “polyhydramnios”.

Both are associated with more complications in pregnancy. If either of these are present, there is a higher chance of having a premature baby and a higher chance of stillbirth. There can also be more difficulties in labour and delivery. There is a higher chance of needing an assisted birth (forceps or ventouse or Caesarean section) and higher chance of shoulder dystocia, where the baby can become stuck in the birth canal.

All these complications can be reduced by aiming for your blood sugars to be as normal as possible. Shortly after birth, the baby may also continue to produce extra insulin and this can cause its blood sugar to drop too low (hypoglycaemia). This can affect the baby’s ability to maintain its temperature and it can have an increased risk of infection and jaundice and need admission to Special Care.

The baby’s blood glucose levels will be observed during the first 12-24 hours of life while still in the hospital. This does not mean that the baby has diabetes, and its blood glucose will return to normal once a feeding pattern is established. If low blood glucose in your baby is identified quickly, it is easily treated by being fed. Breastfeeding is strongly recommended and research suggests that this may protect against childhood diabetes and obesity.

Children whose mothers have been affected by GDM are at greater risk of developing diabetes and obesity later in life.

If you are planning to breastfeed you can start to hand express and collect your breastmilk (called colostrum) to encourage your milk supply and to help stabilise your baby’s blood sugar levels. This can be done safely from 36 weeks of pregnancy and you can ask your community midwife for a colostrum collection kit and further information.

How will it affect my birth?

You will be offered continuous monitoring of your baby’s heartbeat throughout labour. Your blood glucose will be checked regularly during labour and you may need extra insulin to bring your sugars to normal. The doctors on Labour Ward will be aware of your diabetes and may discuss interventions such as assisted birth or Caesarean section.

There is a higher chance of shoulder dystocia, an emergency situation where the baby’s shoulder is stuck behind your pubic bone. This usually can be resolved with simple manoeuvres, however in a very small number of cases, the baby can have nerve damage in their arm needing physiotherapy, or they can lack oxygen potentially leading to brain damage. The chance of this is extremely small, please discuss any concerns with your midwife or doctor.

What will happen after the baby is born?

Generally gestational diabetes goes away after the baby is born, however some people can have underlying Type 2 Diabetes. You should arrange to have a fasting blood glucose test with your GP 6 – 8 weeks after your baby is born.

Future lifestyle choices

Having GDM increases your risk of developing diabetes later in life. Up to 50% of women with gestational diabetes will develop Type 2 Diabetes within 5 years. We recommend you continue with the healthy lifestyle changes (diet and exercise) and aim to have a normal weight (BMI 20 – 25). You will need to have an annual diabetes screen and blood pressure check with your GP.

Symptoms of diabetes to look out for are increased thirst, passing urine more frequently, weight loss and excessive tiredness. Your GP will offer to refer you to the Diabetes Prevention Programme.

GDM is likely to reoccur in future pregnancies, therefore you should inform your midwife or GP as soon as you think that you may be pregnant so that you can be offered the appropriate care.

Dietary advice

  • Eat regular, balanced meals which include one or two small portions of slow release wholegrain carbohydrate (eg brown rice, brown pasta). Include more protein eg lean meat, chicken, fish or eggs and lots of vegetables or salad. Also include some dairy foods such as milk, sugar free yoghurt and cheese.
  • Other good carbohydrate choices include wholemeal brown pasta, basmati, brown or easy cook rice, grainy breads such as granary, multiseed/grain, pumpernickel and rye, new potatoes (skin on), sweet potato, original porridge oats, and natural unsweetened muesli.
  • Aim for at least five portions of fruit and vegetables a day to provide vitamins, minerals and fibre but limit yourself to one portion of fruit at a time. Try to include beans and lentils such as kidney beans, butter beans, chickpeas or red and green lentils.
  • Eat small amounts of unsaturated fat to keep your body healthy and reduce cholesterol levels. Unsaturated fats include: nuts and seeds, avocados, sunflower, olive and vegetable oils and spreads made from these oils.
Foods to Avoid or Reduce Alternatives
Sugar, honey

Sweets, chocolates, mints

Jam and marmalade

Fizzy drinks, e.g. cola, Lucozade, smoothies and fresh fruit juice

Ordinary squash

Tinned fruit in syrup

Milk puddings, e.g. custard, rice pudding

Low fat yoghurts or ordinary yoghurts

Sugar coated breakfast cereals, e.g. Frosties, Coco Pops, Crunchy Nut, Cornflakes, Sugar Puffs

Iced, chocolate covered or cream filled cakes and biscuits

Small amounts of sweeteners eg Splenda

Small amount of dark chocolate

Peanut butter or marmite

Small amounts of diet fizzy drinks or water

No added sugar squash

Fresh fruit x 1

Milk puddings made with less sugar or small amounts of sweeteners e.g. Splenda

Low sugar, plain or greek yoghurt (less than 80 kcal per 125g pot)

Wholegrain unsweetened cereals, eg Branflakes,
porridge, low sugar Muesli, Weetabix

Tea cakes, scones, malt loaf, plain biscuits, e.g. Rich Tea or Digestives x 1-2