Prevention of gestational diabetes mellitus: Where are we now?

Gestational diabetes mellitus (GDM) is increasing at a rapid rate, driven by the increasing proportion of the population that is overweight/obese from a young age. More than 25 randomized controlled trials testing whether GDM can be prevented have now reported their findings, but only four different interventions have shown a reduction in the proportion of women with GDM (healthy eating alone, healthy eating with physical activity, myoinositol supplementation and probiotic treatment), and these results have not been replicated. The interventions tested to date include different diets and different forms of physical activity, in combination or alone, vitamin D, myoinositol, probiotics and metformin. Studies could be improved by using the International Association of Diabetes and Pregnancy Study Group criteria for GDM (which are probably more sensitive to change because of their multiple time points), targeting and tailoring interventions to subgroups most likely to benefit, and separating those with GDM early in pregnancy from those developing GDM de novo. The greatest societal benefit is likely to arise from population-based lifestyle approaches which include those women yet to become pregnant and those who are already pregnant and their families; an approach that is yet to be fully tested.