I'm 29 weeks pregnant with my third child and I have just been told that I need to have a test for gestational diabetes next week. I don't know what gestational diabetes is, and should I be doing anything right now?

Gestational diabetes is a type of diabetes that occurs in pregnancy and means that you cannot control your blood sugar levels properly. It usually resolves after pregnancy with your blood glucose levels returning to normal, however, having gestational diabetes does increase your risk of developing gestational diabetes in future pregnancies and, increases your chances of developing diabetes later in life. It can also increase the risks for mum and baby.

At the antenatal booking appointment women are assessed for risk factors that can make gestational diabetes more likely. These include:

• being very overweight
• a family history of diabetes
• an unexplained stillbirth or neonatal death in a previous pregnancy
• a very large baby in a previous pregnancy
• 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 may be asked to have a test for gestational diabetes. The test is called an Oral Glucose Tolerance Test. This involves a blood test before breakfast, then again two hours after a glucose drink.

Once diagnosed women with diabetes should aim to keep their fasting blood glucose between 3.5 and 5.9 mmol/litre and 1-hour post meal blood glucose below 7.8 mmol/litre. You will be taught how to test your own levels. Often, blood glucose levels can be controlled by diet. You will be referred to a dietitian who will advise you about healthy eating. If your blood glucose cannot be controlled by diet, you may need tablets or insulin to treat your diabetes (this applies to about 10 - 20 per cent of women).

It is better not to change your diet at the moment until you have had the test for gestational diabetes.

See www.diabetes.org.uk for more information.