Dieting and exercise may not stop the onset of gestational diabetes mellitus (GDM), say US researchers, who suggest early screening for dysglycaemia in all women may prove a more effective prevention strategy.

The study of 62 obese pregnant women over 12 weeks in their second trimester found the energy balance (intake vs expenditure) was similar in the nine women who developed GDM compared with the rest of the participants.

Both energy intake (2744kcal/day vs 2606kcal/day) and energy expenditure (2855kcal/day vs 2631kcal/day) were comparable between the two groups, the team from Pennington Biomedical Research Center reported in Cell Metabolism.

Physical activity over seven days was also similar, as were the results of indirect calorimetry in a respiratory chamber to measure energy expenditure during sleep and the micronutrient content of the participants’ meals, which was validated by food photography.