Gestational diabetes is associated with change in the gut microbiota composition in third trimester of pregnancy and postpartum

Background Imbalances of gut microbiota composition are linked to a range of metabolic perturbations. In the present study, we examined the gut microbiota of women with gestational diabetes mellitus (GDM) and normoglycaemic pregnant women in late pregnancy and about 8 months postpartum. Methods Gut microbiota profiles of women with GDM (n = 50) and healthy (n = 157) pregnant women in the third trimester and 8 months postpartum were assessed by 16S rRNA gene amplicon sequencing of the V1-V2 region. Insulin and glucose homeostasis were evaluated by a 75 g 2-h oral glucose tolerance test during and after pregnancy. Results Gut microbiota of women with GDM was aberrant at multiple levels, including phylum and genus levels, compared with normoglycaemic pregnant women. Actinobacteria at phylum level and Collinsella, Rothia and Desulfovibrio at genus level had a higher abundance in the GDM cohort. Difference in abundance of 17 species-level operational taxonomic units (OTUs) during pregnancy was associated with GDM. After adjustment for pre-pregnancy body mass index (BMI), 5 of the 17 OTUs showed differential abundance in the GDM cohort compared with the normoglycaemic pregnant women with enrichment of species annotated to Faecalibacterium and Anaerotruncus and depletion of species annotated to Clostridium (sensu stricto) and to Veillonella. OTUs assigned to Akkermansia were associated with lower insulin sensitivity while Christensenella OTUs were associated with higher fasting plasma glucose concentration. OTU richness and Shannon index decreased from late pregnancy to postpartum regardless of metabolic status. About 8 months after delivery, the microbiota of women with previous GDM was still characterised by an aberrant composition. Thirteen OTUs were differentially abundant in women with previous GDM compared with women with previous normoglycaemic pregnancy. Conclusion GDM diagnosed in the third trimester of pregnancy is associated with a disrupted gut microbiota composition compared with normoglycaemic pregnant women, and 8 months after pregnancy, differences in the gut microbiota signatures are still detectable. The gut microbiota composition of women with GDM, both during and after pregnancy, resembles the aberrant microbiota composition reported in non-pregnant individuals with type 2 diabetes and associated intermediary metabolic traits. Electronic supplementary material The online version of this article (10.1186/s40168-018-0472-x) contains supplementary material, which is available to authorized users.

connecting samples from the same individual. Differences between normoglycaemic and GDM pregnancies were tested using Students ttest. Difference in richness, Shannon diversity and Pielou evenness between time points in GDM and normoglycaemic women combined was tested using a paired t-test.

Figure S5. Relationship between glycaemic traits and alpha diversity
Scatter plots showing the relationships between four glycaemic traits (fasting and 2 h stimulated plasma glucose, insulin sensitivity, and disposition index; log 10 scaled) and three measures of alpha diversity (observed OTUs, Shannon's diversity index, and Pielou's evenness index). Regression lines with 95% confidence intervals are plotted for women with GDM (here noted as red diabetic) and normoglycaemic women individualy. P indicate the nominal significance of the linear relationship between each glycaemic trait and alpha diversity measure (linear regression) in normoglycaemic women and women with GDM combined. P interaction indicate the nominal significance of the interaction between alpha diversity and GDM status for each combination of alpha diversity measure and glycaemic trait.

Figure S6. Phylum level composition in pregnant women with gestational diabetes and with normal glucose regulation
Mean (standard deviation) read count at a rarefied sequencing depth of 10,000 reads per samples. Only phyla with a mean read count 1 in women with gestational diabetes or in women with normal glucose regulation are depicted. Figure S7. Family level composition in pregnant women with gestational diabetes and with normal glucose regulation.

Figure S8. Genus level composition in pregnant women with gestational diabetes and with normal glucose regulation.
Mean (standard deviation) read count at a rarefied sequencing depth of 10,000 reads per samples. Only genera with a mean read count 10 in women with gestational diabetes or in women with normal glucose regulation are depicted.

Figure S9. Bacterial operational taxonomic units associated with glycaemic traits during pregnancy
Samples were divided into tertiles based on fasting plasma glucose, stimulated 2h glucose, insulin sensitivity, and disposition index respectively. The plot depicts the log 2 fold difference in operational taxonomic unit (OTU) abundance between women in the upper tertile (T3) compared to the lower tertile (T1) of each glycaemic trait tested using the negative binomial Wald test implemented in the DESeq2 R package. Only OTUs significantly associated with either of the four traits at a 10% false discovery rate are depicted. Names are given at the genus level. OTUs are ordered alphabetically by genus annotation. Results in tabular form are available in Table S5. * Q<=0.1 ** Q<=0.05

Figure S10. Bacterial operational taxonomic units associated with glycaemic traits during pregnancy adjusted for pre-pregnancy BMI
Samples were divided into tertiles based on fasting plasma glucose, stimulated 2h glucose, insulin sensitivity, and disposition index respectively. The plot depicts the log 2 fold difference in operational taxonomic unit (OTU) abundance between women in the upper tertile (T3) compared to the lower tertile (T1) of each glycaemic trait tested using the negative binomial Wald test implemented in the DESeq2 R package. Only OTUs significantly associated with either of the four traits at a 10% false discovery rate are depicted. Names are given at the genus level. OTUs are ordered alphabetically by genus annotation. Results in tabular form are available in Table S6. * Q<=0.1 ** Q<=0.05 .

Figure S15. Relationship between glycaemic traits and alpha diversity adjusted for pre-pregnancy BMI
Scatter plots showing the relationships between four glycaemic traits (fasting and 2 h stimulated plasma glucose, insulin sensitivity, and disposition index; log 10 scaled) and three measures of alpha diversity (observed OTUs, Shannon's diversity index, and Pielou's evenness index). Regression lines adjusted for pre-pregnancy BMI with 95% confidence intervals are plotted for women with GDM (here in red noted as diabetic) and normoglycaemic women individually. P indicate the nominal significance of the linear relationship between each glycaemic trait and alpha diversity measure adjusted for pre-pregnancy BMI (linear regression) in normoglycaemic women and women with GDM combined. P interaction indicate the nominal significance of the interaction between alpha diversity and GDM status adjusted for pre-pregnancy BMI for each combination of alpha diversity measure and glycaemic trait.