Low-Carbohydrate Diets, Nutritional Adequacy, Glycemia, and Perinatal Outcomes in Women With Gestational Diabetes Mellitus: A Secondary Analysis of the DiGest Trial.

OBJECTIVE

The optimal dietary carbohydrate intake for pregnant women is disputed internationally. Many authorities recommend a minimum of 175 g/day of carbohydrates primarily to support maternal brain glucose requirements and normal fetal brain development. We assessed whether low (<175 g/day) or very low (<120 g/day) carbohydrate intake was associated with altered nutrient intake, glycemia, or pregnancy outcomes in women with gestational diabetes mellitus (GDM).

RESEARCH DESIGN AND

METHODS

Women recruited to the Dietary Intervention in Gestational Diabetes Trial (DiGest) completed masked continuous glucose monitoring and a 24-h dietary recall at baseline before random assignment to receive either a standard- (2,000 kcal/day) or reduced-energy diet (1,200 kcal/day) from ∼29-36 weeks' gestation.

RESULTS

At baseline, 215 women completed a dietary assessment, of whom 66 (30.7%), 74 (34.4%), and 75 (34.9%) reported standard (≥175 g/day), low (120-175 g/day), and very low carbohydrate intake (<120 g/day), respectively. Women consuming fewer carbohydrates consumed less energy, less dietary fiber, and fewer vitamins (B and E) and minerals but proportionally more protein and fat. Consumption of <120 g/day carbohydrates as assessed at baseline before the intervention was associated with a lower time above range (TAR) >120 mg/dL (-6.8% [95% CI -13.4% to -0.2%]; P = 0.044) and lower birth weight (-9.6 [95% CI -18.7 to -0.6] centiles; P = 0.037), but no difference in large- or small-for-gestational-age birth weight was observed. Low carbohydrate intake as a proportion of total energy intake (<35%) without energy restriction was associated with reduced TAR but not with a difference in birth weight.

CONCLUSIONS

Lower carbohydrate intake at baseline was associated with modestly improved glycemia before random assignment in women with GDM, but vigilance to maintain adequate intake of micronutrients and fiber is required.