Pregnancy-related diabetes: reducing the risk of complications

If you’re pregnant, it can be worrying to find out you have developed diabetes. But new research has found that treating even the mildest form of pregnancy-related diabetes can reduce the risk of a caesarean delivery and other birth complications.

What do we know already?
If you develop diabetes during pregnancy, this is called gestational diabetes. It means that you have high levels of sugar (glucose) in your blood. As a result, your baby gets extra glucose as well. This may mean your baby is larger than average at birth, which can increase the risk of a caesarean section and other problems, such as injury to your baby’s shoulders during delivery. Women with gestational diabetes are also more likely to develop high blood pressure while pregnant, as well as a related condition called pre-eclampsia, which can lead to seizures and, in rare cases, death. Gestational diabetes has also been linked to infant deaths on occasion, as well as a higher risk of diabetes later in life for both mother and baby.

As a result, pregnant women in the UK are routinely tested for gestational diabetes if they have certain risk factors, such as being overweight or having a relative with diabetes. For women diagnosed with the condition, treatment usually involves changing their diet and exercising. If this doesn’t bring their blood sugar level back to normal, doctors then prescribe medicines such as insulin.

However, there haven’t been many studies looking at women who have only mild gestational diabetes and whether treatment is helpful if a woman’s blood sugar level is only slightly raised. Now, researchers have done one of the first large, good-quality studies to explore this question.

What does the new study say?
The study included 958 women with mildly raised blood sugar levels who were between 24 and 31 weeks of pregnancy. Roughly half received nutritional counselling and diet advice, and they monitored their own blood sugar daily. If their blood sugar stayed high, they were treated with insulin. The other women received usual pregnancy care from their doctor.

The study found that women with mild gestational diabetes were less likely to have a caesarean delivery and other pregnancy- and birth-related problems if they had treatment. They were less likely to have unusually large or heavy babies, and their babies were less likely to have shoulder damage at birth.

Women who had treatment also gained less weight during pregnancy and had fewer preterm births. They were also less likely to have blood pressure problems, with only 8.6 percent developing high blood pressure or pre-eclampsia, compared with 13.6 percent in the usual care group.

How reliable are the findings?
The findings should be fairly reliable, as the study was large and carefully done. This type of study is called a randomised controlled trial, which is the best type of study for finding out the effects of a treatment.

Where does the study come from?
The study was done at 14 medical centres around the USA and was funded by grants from the US government and research foundations. It was published in the New England Journal of Medicine, which is owned by the Massachusetts Medical Society.

What does this mean for me?
If you are pregnant and develop mild gestational diabetes, this study shows that treatment can help both you and your baby. There’s a good chance you’ll be able to lower your blood sugar level by making changes to your diet, without needing medicine.

What should I do now?
If you’re pregnant, you should have regular check-ups that may include a test for gestational diabetes. Your doctor is likely to recommend the test if:

• You’re overweight
• You have a parent, brother, or sister with diabetes
• You belong to a high-risk ethnic group (South Asian, black Caribbean, or Middle Eastern)
• You have had gestational diabetes before
• You have had a large baby weighing more than 4.5 kilograms (about 9 pounds, 9 ounces).

If you do test positive for gestational diabetes, make sure you follow your doctor or midwife’s treatment recommendations, even if your blood sugar level is only slightly raised.