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

Abstract

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.