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 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.