A higher-complex carbohydrate diet in gestational diabetes mellitus achieves glucose targets and lowers postprandial lipids: a randomized crossover study

Abstract

Objective: The conventional diet approach to gestational diabetes mellitus (GDM) advocates carbohydrate restriction, resulting in higher fat (HF), also a substrate for fetal fat accretion and associated with maternal insulin resistance. Consequently, there is no consensus about the ideal GDM diet. We hypothesized that, compared with a conventional, lower-carbohydrate/HF diet (40% carbohydrate/45% fat/15% protein), consumption of a higher-complex carbohydrate (HCC)/lower-fat (LF) Choosing Healthy Options in Carbohydrate Energy (CHOICE) diet (60/25/15%) would result in 24-h glucose area under the curve (AUC) profiles within therapeutic targets and lower postprandial lipids.

Research design and methods: Using a randomized, crossover design, we provided 16 GDM women (BMI 34 ± 1 kg/m2) with two 3-day isocaloric diets at 31 ± 0.5 weeks (washout between diets) and performed continuous glucose monitoring. On day 4 of each diet, we determined postprandial (5 h) glucose, insulin, triglycerides (TGs), and free fatty acids (FFAs) following a controlled breakfast meal.

Results: There were no between-diet differences for fasting or mean nocturnal glucose, but 24-h AUC was slightly higher (∼6%) on the HCC/LF CHOICE diet (P = 0.02). The continuous glucose monitoring system (CGMS) revealed modestly higher 1- and 2-h postprandial glucose on CHOICE (1 h, 115 ± 2 vs. 107 ± 3 mg/dL, P ≤ 0.01; 2 h, 106 ± 3 vs. 97 ± 3 mg/dL, P = 0.001) but well below current targets. After breakfast, 5-h glucose and insulin AUCs were slightly higher (P < 0.05), TG AUC was no different, but the FFA AUC was significantly lower (∼19%; P ≤ 0.01) on the CHOICE diet.

Conclusions: This highly controlled study randomizing isocaloric diets and using a CGMS is the first to show that liberalizing complex carbohydrates and reducing fat still achieved glycemia below current treatment targets and lower postprandial FFAs. This diet strategy may have important implications for preventing macrosomia.

Figure 1

CGMS data portraying patterns of glycemia within 16 pregnant women with GDM during 3 days each of diet treatment (LC/CONV [gray] vs. HCC/LF CHOICE [black]). Two-hour postprandial glucose response for (A) breakfast, (B) lunch, and (C) dinner and (D) average of three meals (mean over 2 days). Data are aligned for meal start times. (E and F) Twenty-four-hour pattern of glycemia and glucose AUC with difference between diets. Data are aligned for time beginning at 2330; not aligned for meals although women consumed meals during similar time frames. Mean ± SEM. *, P < 0.05.

Figure 2

(A–D) Five-hour postprandial response to breakfast (30% of total EI) within 16 diet-controlled women with GDM. The meal study took place on the research unit after 3 days each of diet treatment (LC/CONV versus HCC/LF CHOICE). Data are plasma/serum, mean ± SEM. EI, energy intake.