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Importance of dietary interventions for gestational diabetes highlighted

By Bianca Nogrady
A meta-analysis has highlighted the need for better quality dietary interventions for women with gestational diabetes mellitus (GDM).

Writing in Diabetes Care, researchers reported their systematic review and meta-analysis of 18 randomised controlled trials that examined the effect of dietary interventions in 1151 women with GDM, glucose intolerance or hyperglycaemia during pregnancy.

They found that, compared with a control of standard diet, modified diets were associated with significantly larger decreases in both fasting and postprandial glucose, and a 35% reduction in the need for medication.

Sixteen trials also found dietary interventions were associated with significantly lower infant birth weights and a 51% lower incidence of macrosomia.

The dietary interventions used in the studies included low-GI, Dietary Approaches to Stop Hypertension (DASH), low-carbohydrate, soy-protein-enriched and energy-restriction diets.

Of these, the low-GI and DASH diets showed the largest decreases in fasting and postprandial glucose; the DASH diet showed significant benefits in HbA1c, HOMA insulin resistance index, medication need, infant birth weight and macrosomia; and the soy-protein-enriched diet showed significant decreases in medication use and birth weight.

However, the study’s authors noted that the quality of evidence for the study outcomes was low, and baseline differences in postprandial glucose may have impacted the glucose-related outcomes.

In an accompanying editorial, Professor Jennie Brand-Miller and co-author noted that nutrition therapy had become a weak point in the management of GDM, ‘such that despite our strength, we have limped forward in generating clinical evidence to substantiate the potential for nutrition in GDM’.

Speaking to Endocrinology Today, Professor Brand-Miller, from the Charles Perkins Centre at The University of Sydney, said the challenge with assessing dietary interventions was to ensure than the control group had the same amount of professional attention as the intervention group, so-called ‘attention placebo’.

‘What we do know is if you make some effort to modify the composition of the diet, we can improve the outcomes for the pregnancy and for the baby,’ Professor Brand-Miller said. ‘What we don’t know is whether that attention is just attention, or if it is actually something to do with the dietary advice that’s being given.’

Professor Brand-Miller said her own research always included an appropriate control group, and suggested low-GI diets produced the healthiest outcomes with respect to micronutrient intake.
Diabetes Care 2018; 41: 1346-1361.