Pregnancy and gestational diabetes screening
Gestational diabetes (GDM) is a condition resulting in high blood sugar (glucose) levels that is first found during pregnancy.
Gestational diabetes affects up to 1 in 20 pregnancies in the UK.
Almost all women have some degree of impaired glucose tolerance as a result of hormonal changes that occur during pregnancy. That means that their blood sugar may be higher than normal, but not high enough to have diabetes.
Usually the mother's pancreas is able to produce more insulin (about three times the normal amount) to overcome the effect of the pregnancy hormones on blood sugar levels. If, however, the pancreas cannot produce enough insulin to overcome the effect of the increased hormones during pregnancy, blood sugar levels will rise, resulting in gestational diabetes.
Diabetes in pregnancy that is not well managed can causes complications, including birth defects and an increased risk of a miscarriage.
Gestational diabetes risk factors
You may be at increased risk of developing gestational diabetes if:
- Your body mass index ( BMI) is over 30
- You've had a baby previously weighing 4.5kg (10lbs) or more at birth
- You had gestational diabetes in an earlier pregnancy
- You have a close family history of diabetes
- You have South Asian, black Caribbean, or Middle Eastern family origins
Gestational diabetes screening
The NHS recommends every pregnant woman with one or more risk factors should be offered a screening test for gestational diabetes.
Depending on your risk factors, you may be screened for gestational diabetes at varying stages of your pregnancy.
The test for gestational diabetes is an oral glucose tolerance test (OGTT).
What is the oral glucose tolerance test for gestational diabetes?
For an oral glucose tolerance, a sample of your blood will be tested. You will then be given a sweet glucose drink. This is usually carried out before breakfast. Next, more blood tests will be done every half an hour for two hours. This tells doctors how well your body deals with the glucose.
Gestational diabetes test results
If the tests done earlier in pregnancy show you do not have gestational diabetes, you may still be asked to have another test at around weeks 24-28.
If you are diagnosed with gestational diabetes, you will be given advice about how to manage the condition and how to monitor your blood glucose levels yourself at home.
Read more about managing gestational diabetes in pregnancy.