Multiethnic GDM study points to unique gut microbiome profile

Women with gestational diabetes mellitus (GDM) share a common gut bacterial profile regardless of ethnic differences, according to a Singapore study, suggesting a role for specific gut bacteria in GDM pathophysiology.

Analyses of faecal samples from pregnant women with GDM (n=53) and healthy pregnant women (n=16) showed that GDM was associated with gut dysbiosis, with increased abundance of Firmicutes and Actinobacteria and decreased amounts of Bacteroides and Proteobacteria populations. This gut bacterial pattern was consistent across different Asian ethnicities. [Sci Rep 2024;14:9855]

Specifically, bacterial genera such as Collinsella, Blautia, Bifidobacterium, Dorea, Roseburia, Coprococcus, Anaerostipes, Ruminococcus gnavus group, Ruminococcus torques group, Eubacterium hallii group, Romboutsia, Fusicatenibacter, Clostridium sensu stricto 1, Agathobacter, Ruminococcus, and Megasphaera were highly abundant in the GDM group (p<0.05). This pattern contributed to higher Firmicutes to Bacteroidota (F/B) and lower Bacteroidota to Actinobacteriota (B/A) ratios.

Additional data indicated that even with intensive dietary and lifestyle modifications between the second (24–28 weeks) and third (36–40 weeks) trimesters, women with GDM maintained similar levels of gut bacteria diversity, raising questions about the effectiveness of classic GDM management in modifying gut microbiota.

Interestingly, the gut bacteria composition in healthy pregnant women (n=16) varied across ethnicities, unlike the consistent pattern observed in those with GDM. This indicates that ethnicity does influence gut microbiome profiles in pregnancies not complicated by GDM, the investigators noted.

“Differences in gut microbiome might be attributed to variations in several factors in study populations—those that predate the pregnancy such as obesity, body mass index, insulin sensitivity, adiposity, dietary habit, proinflammatory conditions, and ethnicity, and those that arise in pregnancy such as weight gain and foetal factors (eg, sex),” the investigators explained.

“It is conceivable that the antenatal persistence of low-grade inflammation, increase in weight gain, and excessive adipose deposition, might collectively alter the gut microbiome metabolic responses to the pregnancy, hence promoting the development of insulin resistance and GDM,” they said.

The investigators called for multi-omics-based longitudinal studies conducted from preconception to the postpartum period and involving more diverse ethnicities around the world (either in native or immigrant populations) to determine the extent to which gut dysbiosis is driving the GDM pathophysiological process.

“Subsequently, meta-transcriptomics studies can also be performed to establish functionality and relate that to maternal glycaemia and other metabolic parameters as well as GDM-related clinical outcomes, and finally lead to the development of innovative therapeutic strategies,” they added.