Gestational diabetes mellitus (GDM) is a type of diabetes that arises during pregnancy (usually during the second or third trimester).

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.

How will I know if I have it?

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 Type 2 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.

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

Useful Resources

Diabetes UK: Find out all you need to know about Gestational Diabetes

Eating well with Gestational Diabetes (PDF, 12 A4 pages): Dietary advice for women when diabetes occurs during pregnancy.

Antenatal Expressing Leaflet: Advice from the Great Western Hospital for diabetic mothers who plan to breastfeed.

Guide to Gestational Diabetes – information from Diabetes UK for expecting mothers who have been diagnosed with the condition.