Dietary intervention in patients with gestational diabetes mellitus: a systematic review and meta-analysis of randomized clinical trials on maternal and newborn outcomes.

OBJECTIVE Diet is the cornerstone treatment of patients with gestational diabetes mellitus (GDM), but its role in maternal and newborn outcomes has been scarcely studied. The purpose of this study was to analyze the efficacy of dietary interventions on maternal or newborn outcomes in patients with GDM. RESEARCH DESIGN AND METHODS A systematic review and meta-analysis of randomized clinical trials (RCTs) of dietary intervention in GDM or pregnancy with hyperglycemia was performed. MEDLINE, Embase, ClinicalTrials.gov, Cochrane, and Scopus were searched through to March 2014. The main evaluated maternal outcomes were proportion of patients using insulin and proportion of cesarean delivery; the newborn outcomes were proportion of macrosomia and hypoglycemia and newborn weight. RESULTS From 1,170 studies, nine RCTs, including 884 women aged 31.5 years (28.7-33.2) with 27.4 weeks (24.1-30.3) of gestation, were eligible. We divided the RCTs according to the type of dietary intervention: low glycemic index (GI) (n = 4; 257 patients), total energy restriction (n = 2; 425 patients), low carbohydrates (n = 2; 182 patients), and others (n = 1; 20 patients). Diet with low GI reduced the proportion of patients who used insulin (relative risk 0.767 [95% CI 0.597, 0.986]; P = 0.039) and the newborn birth weight (weight mean differences -161.9 g [95% CI -246.4, -77.4]; P = 0.000) as compared with control diet. Total restriction and low carbohydrate diets did not change either maternal or newborn outcomes. CONCLUSIONS A low GI diet was associated with less frequent insulin use and lower birth weight than control diets, suggesting that it is the most appropriate dietary intervention to be prescribed to patients with GDM.