What is gestational diabetes?
Gestational diabetes mellitus (GDM) is a type of diabetes that usually occurs in the middle or towards the end of pregnancy (usually in the second trimester). GDM is any kind of sugar impairment developed in pregnancy at any gestation.
GDM usually disappears after your baby has been born, although there is a greater chance that you may develop diabetes in later life.
How does GDM develop?
During pregnancy your body makes high levels of pregnancy hormones and this can reduce the effectiveness of how well your insulin works. If you cannot make enough insulin or your body cannot use the insulin effectively your blood glucose levels rise. This is called insulin resistance.
How common is GDM?
It is common, and it affects at least four-to-five in 100 women during pregnancy.
- You are more likely to develop the condition if you have any of the following risk factors:
- your body mass index (BMI) is 30 or higher
- you have previously given birth to a baby weighing 4.5 kg (10 lbs) or more
- you have had GDM before
- you have a parent, brother or sister with diabetes
- your family origin is South Asian, Chinese, African-Caribbean or Middle Eastern.
What are the risks of having GDM?
If you have GDM, you may be at risk of:
- having a large baby, which increases the likelihood of birth problems, such as shoulder dystocia
- having your labour induced and caesarean section
- developing Type 2 diabetes.
Your baby may be at risk of:
- health problems following birth that may require hospital care/ Neonatal admission
stillbirth - being at greater risk of developing obesity and/or diabetes in later life.
Management of GDM
The specialist midwife will discuss an individual plan of healthy eating and lifestyle. A dietician referral is also offered. You will be shown how to monitor your blood glucose levels at home and have regular reviews with the specialist midwife and Obstetric Team. Your care pathway will be transferred to consultant-led management.
If your blood glucose levels cannot be controlled by diet and exercise alone you may require medication. Depending on your diabetes control, the Diabetic Team will review your blood sugars up to three times a week.
Up to 50% of women with GDM will require medication in their pregnancy. Regular growth scans and review of blood sugar control will aid you and the obstetric team to plan a safe birth for your baby.
A planned birth at 39-40+6 weeks' gestation will be discussed with the obstetric consultant.
Monitoring GDM
We will provide you with a blood glucose monitor and teach you how to use it. You will need to test your blood four times a day.
Aim to keep Blood Glucose levels between
- 4-5.3 mmol fasting (before breakfast)
- 4-7.8 mmol one hour after main meals (breakfast, lunch and dinner)
Record all your blood glucose readings- If you are connected to the ‘Mysugr’ app, your blood sugar readings will be transferred via Bluetooth to an online platform where you and health professionals can view them. If we are unable to connect you, we will give you a document to write them down manually. Please ensure you bring this document to all appointments for health professionals to review.
Monitoring and prescriptions
A GP letter will be given to you at the time of your teaching session for the equipment used to test your blood sugars. Please ensure you take this letter immediately to your GP, in order that you will have sufficient supplies to monitor at home. The letter is a repeat prescription, therefore please call your GP for a repeat prescription when your supplies are low. Please ensure you have enough supplies if admitted to hospital, as the ward do not supply strips and needles for testing.
Care pathways
Upon diagnosis of GDM, you will be given approximately two weeks to make changes to your diet and lifestyle. The Diabetic Team will arrange a telephone review to assess your pathway and management for the rest of the pregnancy.
During your pregnancy, your healthcare professionals will give you information and advice about:
- planning birth, including timing and types of birth, pain relief and changes to your medications during labour and after your baby is born
- looking after your baby following birth
- care for you after your baby is born including contraception
- possible induction of labour or Caesarean section if appropriate at 39-40 weeks for those on treatment, or 40-40+6 for those who are diet-controlled
Healthy eating in pregnancy
The most important treatment for GDM is a healthy eating plan and exercising regularly. Walking for 30 minutes after a meal can help with controlling your blood glucose levels. GDM usually improves with these changes. You should have an opportunity to talk to a healthcare professional about choosing foods that will help to keep your blood glucose at a healthy and stable level.
If you consent, you will be referred to the dietician and a teaching session will be arranged to discuss in more depth healthy eating and nutrition. Please refer to the document provided for dietary advice by our dietician.
Medication
Metformin
The first line treatment is Metformin instant release tablet (IR). Slow release Metformin (Metformin SR) may be offered if you are unable to tolerate Metformin IR or as trial to stabilise fasting blood sugars. The maximum dose of Metformin is 2g daily in divided doses.
If prescribing Metformin to a patient, please issue a GP letter/request to continue supply after 30 days, and allow two weeks to assess if metformin treatment is improving blood sugar ranges. However, if indicated, recommend insulin therapy sooner as a second line of treatment.
Insulin
The most common insulin products used in pregnancy are:
Novorapid Flexpen
Given before mealtimes; the starting dose is normally two units and can be increased weekly if indicated
Humulin I Kwikpen
Given before bed, the starting dose is normally two units and titrated as indicated
Insulin can be increased every three days if blood sugar ranges are significantly high. If unsure please liaise with DSM/DSN for further input and advice.
Some pre-existing diabetic patients may be on other insulin injections such as Levemir, Humalog, Insulatard, Lanctus etc.
Other useful information
For more information about diet, visit:
Diabetes UK: Gestational diabetes diet
NWL Know Diabetes Diabetes in North West London