Glucose Tolerance Test (GTT) Information
If your midwife has booked you in for a GTT please read the following important information.
There are several reasons why this test is recommended which can be explained by your midwife. Some of the reasons may be:
- if you've previously had gestational diabetes
- if you've had a baby born over the 90th centile or over 4.5kg
- if you have a 1st degree relative (parent or sibling) with Type 1 or Type 2 Diabetes
- if your BMI is over 30
- if your ethic background has a higher prevalence of diabetes
- if you have PCOS
- if you are taking certain anti psychotic medications
- if the growth of your baby is over the 90th centile on scan, or polyhydramnios (increased waters around baby) before 34+6 weeks after this gestation other monitoring/plans will be offered
- if you have ++ glucose in your urine one or + glucose in your urine twice before 34+6 after this gestation other monitoring /plans will be offered
What is a Glucose Tolerance Test?
A glucose tolerance test is used to confirm whether a person has diabetes, a condition in which the body does not use or produce insulin properly to maintain a normal blood glucose level. Some women develop diabetes whilst pregnant. This is known as Gestational Diabetes. It can occur at any stage of pregnancy, but is more common in the third trimester (after 28 weeks) if the body fails to produce enough insulin to meet the additional demands of pregnancy. The test involves consuming a glucose drink and then measuring timed blood glucose levels.
How is the test performed?
You must have nothing to eat from 9pm onwards on the night before your test. When you attend antenatal clinic the following morning, a fasting blood sample will be obtained. You will be given a drink containing glucose and a further blood sample will be taken two hours later.
How should I prepare for the test?
Before the test:
For three days before the test, do not try to restrict or alter your normal eating pattern. During the three days before the test, exercise as normal. Do not eat anything from 9 pm the night before. You may drink only water.
If you are a smoker or use a vape, you must NOT smoke or vape after 9pm on the night before the test as it can affect the results. If you regularly take medicines, take them as usual. If any of these should be taken with food, it may be advisable to delay taking them until after you have had the test. If you are unsure regarding this please contact your GP.
Please provide a list of any medicines that you are taking to the person who does the test as some medicines may affect the test results.
On the morning of the test:
Attend your appointment as indicated in your appointment letter. Please note the test will take two hours. A blood sample will be taken from your arm before you are given a glucose drink which should be drunk within 5 minutes (or as soon as possible).
After 2 hours has elapsed, a second blood sample will be taken. Throughout this time you may continue to drink water. If you are a smoker or use a vape, we advise you NOT to smoke until after the test is completed as smoking/vaping can affect the results. The two blood samples will then be sent to the laboratory for testing. You may eat and drink as normal once the test is completed.
When will I get the results?
You will be contacted by the midwifery team over the next few days if the test confirms gestational diabetes. If the test is normal you will not be contacted and the result will be discussed at your next routine midwifery appointment.
What will it mean to me if the test is abnormal?
If your test shows that your body does not clear glucose quickly enough, you may have Gestational Diabetes. Most women who have diabetes or develop diabetes in pregnancy have healthy pregnancies and healthy babies. However, they may sometimes have complications, so it is important that they receive specialist care and support to ensure that their gestational diabetes is well controlled and they stay well. This condition may not persist postnatally.
Following an abnormal result you will be referred to the next Gestational Diabetes Clinic on a Wednesday afternoon to discuss dietary changes and to start regular blood sugar monitoring. A growth scan will be arranged and you will then be seen regularly in the joint Diabetes Antenatal Clinic on a Monday morning. This is run by a specialist team; comprising of a a specialist Consultant Obstetrician, midwife, an Endocrinologist (Doctor specialising in Diabetes), a Diabetic Nurse and a Dietician who will care for you during your pregnancy.
If you need to rearrange your appointment please contact our Antenatal Clinic Front Desk on 0151 604 7035.