There is evidence that controlling total amount of carbohydrates is a strategy for
controlling glucose levels in diabetes mellitus. There is not major evidence that any given
macronutrient percentage may be recommended to treat a woman with Gestational Diabetes
Mellitus (GDM). In the investigators' country, insulin is the second-line treatment once
medical nutrition therapy (MNT) has failed to control glucose levels during pregnancy.
Insulin treatment is more expensive and not as well accepted as MNT. The investigators have
designed a randomized-controlled trial to assess whether a diet with 40% total calories from
carbohydrates may reduce the need of insulin treatment in women with gestational diabetes,
without having unfavourable pregnancy outcomes, in comparison with a diet with 55% total
calories from carbohydrates.