The association between gestational diabetes and the microbiome: a systematic review and meta-analysis

Abstract

Background: Metabolic diseases, such as metabolic syndrome or type 2 diabetes mellitus, are thought to be influenced by changes in the microbiome. The possible link between diabetes during pregnancy and the microorganisms in the body has become more important, with many studies attempting to uncover this relationship. This systematic review with meta-analysis aims to summarize the evidence relative to the differences in the microbiota composition of different body sites in pregnant women that developed gestational diabetes and their offspring compared to healthy gestations. Results: Twenty-one studies were used for the meta-analyses. The gut was the body site with more quantitative evidence provided. Neither of the most reported phyla presented differences in relative abundance between groups. Only Verrucomicrobia presented a higher relative abundance in the control group, with a standardized mean difference of -0.51 95% CI [-0.87,-0.15], although there was a heterogeneity of 68%, demanding caution when interpreting this result. Regarding genera, Bifidobacterium and Alistipes were observed in higher abundance in control, -0.31 95% CI [-0.50,-0.11] and -0.28 95% CI [-0.53, -0.02], respectively. Conversely, Roseburia appears more abundant in the diabetic group (0.29 95% CI [0.08, 0.51]). Concerning meconium, no statistically significant differences were found in the evaluated phyla or genera. Furthermore, the levels of heterogeneity among studies tend to be considerable. Oppositely, placental microbiota presented low heterogeneity. Firmicutes presented an increase in the diseased group with a standard mean difference of 0.56 [0.20, 0.92], while Proteobacteria had a higher abundance in control (-0.34 [-0.62, -0.05]). Regarding genera, Faecalibacterium, Bacteroides, and Lachnospiraceae uncl. were more abundant in the gestational diabetes group, with mean differences of 0.44 [0.05, 0.83], 0.40 [0.11, 0.70], and 0.32 [0.03, 0.61], respectively, always with 95% Cl. Conclusion: Although this metabolic condition may have some microbial associations, insufficient quantitative evidence impacts the conclusions. Standardization of procedures could be beneficial to fully understand the impact of gestational diabetes on the microbiome and vice-versa.