Gestational diabetes mellitus (GDM) is a glucose intolerance that develops during pregnancy. In pregnancy the woman’s body is not as sensitive to insulin which is needed to lower blood sugar levels. When GDM occurs the body does not produce sufficient insulin. As a result of this insulin insensitivity blood glucose levels rise. GDM is associated with problems for women and their babies including higher rates of intervention during birth, higher birth weights, birth trauma, low blood sugar levels in the baby and jaundice. The Australian Diabetes Council estimates GDM affects up to eight per cent of Australian women during pregnancy.
Changing a pregnant woman’s diet continues to be considered the best way to manage GDM. However while a number of studies have been conducted, there remains a broad range of opinion on what diet works best for women with GDM. Diets offered to women with GDM vary greatly. Diets can include foods that have a moderate glycaemic index (GI), low carbohydrates, high fat or low GI. A diet may also be energy restricted.
Recently the Cochrane Collaboration compared studies that looked at the best diet for women with GDM. They compared nine trials, comprising 429 women and 436 babies, and determine whether connections could be made between a particular diet and improved outcomes for women and babies. Various types of diets where examined as well as whether or not outcomes improved for both mothers and babies. Eleven different types of diets were assessed using six different comparisons:
What the researchers found was that all the studies looked at were small in size making it difficult to draw reliable conclusions about what diet works best for women with GDM. In addition none of the studies looked at the women’s quality of life while following the recommended diet, the impact on sound nutrition or the longer-term health outcomes for babies and mothers.
The findings were surprising. Of the nine studies reviewed, no significant benefit of dietary modification could be found for women or their babies. This includes no obvious reduction in rates of large-for-gestational age (LGA) babies, macrosomia (birth weight greater than 4000 grams), or instrumental or caesarean births.
The researchers concluded that larger trials are required to conclusively determine the value of different diets for women with GDM. In the meantime health professionals should consider the impact on general health of the woman and baby when recommending any dietary modifications. Consideration could include the potential for increases in body mass index (BMI) as a result of a high-monounsaturated diet, or a reduction in the intake of valuable nutrients in high-moderate GI diets, in favour of foods higher in ‘empty kilojoules’. Any changes to a woman’s diet in pregnancy need to be considered carefully.
Han, S., Crowther, C., Middleton, P., & Heatley, E. (2013) Different types of dietary advice for women with gestational diabetes mellitus. Cochrane Pregnancy and Childbirth Group viewed 15 June 2013.
Published on 15/07/2013