A higher-complex carbohydrate compared with conventional low-carbohydrate diet in gestational diabetes mellitus...

Robust randomized controlled trials (RCTs) are unavailable to delineate the effects of nutrition in gestational diabetes mellitus (GDM) on placental-fetal fuel exposures from glucose, triglycerides (TGs), and free fatty acids (FFAs). TG/FFA may increase maternal insulin resistance (IR) and serve as substrates for fetal fat accretion.

In an RCT, we tested the hypothesis that 7-8 wk of a higher-complex carbohydrate (60%)/lower-fat (25%) diet (CHOICE) would result in lower postprandial FFA (prespecified secondary outcome) compared with a conventional lower-carbohydrate (40%)/higher-fat (45%) diet (LC/CONV) in GDM.

After diagnosis (∼28-30 wk), 59 body mass index (BMI)-matched diet-controlled participants with GDM (mean ± standard error of the mean; BMI 32 ± 1 kg/m²) were randomly assigned to a eucaloric LC/CONV or CHOICE diet [7.2 ± 1 wk; all meals provided; 35% saturated fat (of total fat) and 70 ± 5 g/d simple sugars, both diets]. At 30-31 and 36-37 wk after fasting, a breakfast test meal was administered (30% of total calories), and blood was sampled hourly foir 5 hrs. Five-hour glucose, TGs, FFAs, and glycerol areas under the curve (AUCs) were calculated.

Of 59 participants, 13 met exclusion criteria. By analysis of covariance (n = 23/group), weight gain, birthweight, and newborn adiposity were similar. At 36-37 wk, the FFA AUC was 20% higher on LC/CONV compared with CHOICE (P = 0.016), without differences in TG or glycerol. Participants on LC/CONV had 12% lower glucose AUC (P < 0.05). Those on LC/CONV demonstrated a 20% increase in TG AUC and a 15% increase in glycerol AUC (P < 0.05, both) compared with those on CHOICE, who had a 14% increase in TG AUC (P < 0.05) and no change in glycerol AUC.

CHOICE resulted in 20% less postprandial FFA exposure and blunting of the expected rise in TG/glycerol, which may mitigate maternal IR and fetal fat accretion. Glycemic control was clinically acceptable despite a 12% greater postbreakfast glucose exposure. Thus, lower dietary fat and higher-quality carbohydrates produced a synergistic attenuation of TG/FFA with effective glycemic control in GDM. This trial was registered at clinicaltrials.gov registry as NCT02244814.