Effects of Low Glycemic Index Diets on Gestational Diabetes Mellitus: A Meta-Analysis of Randomized Controlled Clinical Trials

Studies of the effects of low glycemic index (LGI) diets on gestational diabetes mellitus (GDM) have reported conflicting findings. The aim of the study was to evaluate the results of randomized controlled trials (RCTs) that investigated the effects of LGI diets with and without added dietary fiber (DF) on maternal and neonatal outcomes in GDM patients. We searched the MEDLINE, EMBASE, EBSCO, Springer, Ovid, and Cochrane Library databases for studies of the effects of LGI diets in GDM patients. We performed a meta-analysis of the effects of the LGI diets with and without added dietary fiber (DF) on GDM outcomes. Risk ratios (RR) and 95% confidence intervals (CIs) were calculated using random- and fixed-effects models. Five RCTs involving 302 participants were included in our meta-analysis. No statistically significant differences in the risks of cesarean section delivery, large for gestational age, and small for gestational age were observed. The risk of macrosomia in the LGI groups was significantly lower (RR = 0.27; 95% CI: 0.10–0.71; P = 0.008) than that in the control groups. Our subgroup analysis of the effects of DF showed that LGI diets with an increased level of DF, relative to the control diet, reduced the risk of macrosomia beyond that of the LGI diets alone (RR: 0.17 vs 0.47, respectively). The subgroup analysis also showed that LGI diets in which the level of DF was approximately equivalent to that in the control diets significantly reduced the risk of insulin usage (RR = 0.69; 95% CI: 0.52–0.92; P = 0.01). The LGI diets reduced the risk of macrosomia in GDM patients, and LGI diets with added DF reduced the risk of macrosomia further. The LGI diets with levels of DF approximately equivalent to that in the control diets reduced the risk of insulin usage in GDM patients.