Effectiveness of carbohydrate counting and Dietary Approach to Stop Hypertension dietary intervention on managing Gestational Diabetes Mellitus among pregnant women who used metformin: A randomized controlled clinical trial

Background Gestational diabetes mellitus (GDM) is one of the most common complication of pregnancy that has significant impacts on both mother and her offspring health. The present study aimed to examine the effect of carbohydrate counting, carbohydrate counting combined with DASH, and control dietary interventions on glycemic control, and maternal and neonatal outcomes. Methods A total of 75 pregnant women with GDM at 24th – 30th week of gestation were enrolled and randomized to follow one of the three diets: control or carbohydrate counting, or carbohydrate counting combined with Dietary Approach to Stop Hypertension (DASH). Only 70 of them completed the study until delivery. Fasting blood samples were taken at baseline and the end of the study to measure fasting blood glucose (FBG), fasting insulin, glycated hemoglobin (HbA1c), and fructosamine. Homeostatic model assessment-insulin resistance (HOMA-IR) score was calculated using HOMA2 calculator program. The participants recorded at least four blood glucose readings per day. Maternal and neonatal outcomes were collected from medical records. Dietary intake was assessed by three-day food records at the baseline and the end of the study. Results Adherence to the three dietary interventions, resulted in decreased FBG levels significantly among all the participants (P < 0.05). Consumption of the carbohydrate counting combined with the DASH diet showed significant reduction in serum insulin levels and HOMA-IR score compared to carbohydrate counting group and control group. Means of fructosamine and HbA1c did not differ significantly among the three intervention diet groups. Overall mean of 1-h postprandial glucose (1 h PG) level was significantly lower in the carbohydrate counting combined with DASH group compared with that in the carbohydrate counting group and the control group (P < 0.001). The number of women who were required to commence insulin therapy after dietary intervention was significantly lower in carbohydrate counting group and carbohydrate counting combined with DASH group (P = 0.026). There were no significant differences in other maternal and neonatal outcomes among the three dietary intervention groups. Conclusions The carbohydrate counting and the carbohydrate counting combined with DASH dietary interventions resulted in beneficial effects on FBG and 1 h PG compared with the control diet. The three dietary interventions produced similar maternal and neonatal outcomes in women with GDM. Trial registration This trial was registered on ClinicalTrials.gov under the identification code: NCT 03244579. https://clinicaltrials.gov/ct2/show/NCT03244579.