A Higher-Complex Carbohydrate vs Conventional Low-Carbohydrate Diet in Gestational Diabetes Mellitus results in Lower Postprandial Free Fatty Acids: A Randomized Controlled Trial.

BACKGROUND

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

OBJECTIVE

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

METHODS

After diagnosis (∼28-30 wks'), 59 BMI-matched diet-controlled participants with GDM (mean±SEM; BMI 32±1 kg/m2) were randomized to a eucaloric LC/CONV or CHOICE diet (7.2±1 wks; all meals provided; 35% saturated fat [of total fat] and 70±5g/d simple sugars, both diets). At 30-31 and 36-37 wks' after fasting, a breakfast test meal was administered (30% of total calories) and hourly blood sampled x5. Five-hour glucose, TG, FFA, and glycerol areas-under-the curve (AUC) were calculated.

RESULTS

Of 59, 13 met exclusions. By ANCOVA (n=23/group), weight gain, birthweight, and newborn adiposity were similar. At 36-37 wks', the FFA AUC was 20% higher on LC/CONV compared to 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 to those on CHOICE, who had a 14% increase in TG AUC (p<0.05) and no change in glycerol AUC.

CONCLUSION/INTERPRETATION: 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 post-breakfast glucose exposure. Thus, lower dietary fat and higher quality carbohydrates produced a synergistic attenuation of TG/FFA with effective glycemic control in GDM.

GOV REGISTRY: NCT02244814, https://clinicaltrials.gov/study/NCT02244814.