Lightning Talk + Poster ESA-SRB-ANZOS 2025 in conjunction with ENSA

Comparison of the gut microbiome composition of pregnant women with Type 2 Diabetes, gestational diabetes and normoglycaemic controls (127146)

Sophie M Leech 1 , Emily S Dorey 2 , Josephine Laurie 3 , Danielle J Borg 4 , Kym M Rae 2 , Vicki L Clifton 2 , James SM Cuffe 5 , Thomas P Mullins 5 , Leonie K Callaway 6 7 , David McIntyre 6 , Helen L Barrett 8 9 , Marloes Dekker Nitert 1
  1. School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, QLD, Australia
  2. Mater Medical Research Institute, South Brisbane, QLD, Australia
  3. Obstetric Medicine, Mater Health Services, South Brisbane, QLD, Australia
  4. Women, Newborn and Children Services, Gold Coast University Hospital, Southport, QLD, Australia
  5. School of Biomedical Sciences, The University of Queensland, St Lucia, QLD, Australia
  6. School of Medicine, The University of Queensland, Herston, QLD, Australia
  7. Women's and Newborns, Royal Brisbane and Women's Hospital, Brisbane, QLD, Australia
  8. Obstetric Medicine, Royal Hospital for Women, Randwick, NSW, Australia
  9. Faculty of Medicine, University of New South Wales, Sydney, NSW, Australia

Pregnancy, diabetes, and diabetes medications have been associated with changes to the composition of the gut microbiome. However, it is unclear if pre-existing Type 2 Diabetes (T2D) differentially affects the composition and function of the gut microbiome, in comparison to women with gestational diabetes (GDM) and normoglycaemia in pregnancy. In addition, the effect of metformin treatment on the gut microbiome during pregnancy is unclear.  

Faecal samples were collected from women with T2DM (n = 9, metformin: n = 7), GDM (n = 29, metformin: n = 8) and normoglycaemic women (n=58) between 24-36 weeks’ gestation as part of three studies conducted in Brisbane, Australia. Metagenomic shotgun sequencing was performed, and the taxonomic and functional profiles were analysed using MetaPhlAn4.0 and HUMAnN3.6. Compositional changes were assessed through alpha and beta diversity, and differential abundance (DA) analysis was conducted using a consensus approach of ALDEx2, ANCOM-BC2, MaAsLin2, LinDA, ZicoSeq and DESeq2 with taxa/pathways only considered significant if 50% of tools identified a significant association. Results were adjusted for study, BMI and ethnicity.  

Due to a high proportion of women with T2DM being treated with metformin, the effect of metformin is assessed in women with GDM only. Examining the richness of the microbiome by diabetes status, women with T2DM but not GDM have a borderline significant decrease in richness (p = 0.05) compared to normoglycaemic women. Neither diabetes status nor metformin use affected beta diversity. DA analysis using the consensus approach identified increases in pathway PWY-8190: ‘L-glutamate degradation XI,’ in association with T2DM. There were no DA taxa or pathways associated with GDM or metformin use. 

Overall, there were minimal differences in the microbiome associated with T2DM or GDM, or metformin use in pregnancy. Further research in a larger cohort is required to confirm this finding.