Objective To investigate the characteristics of gut microbiota in pregnant women with gestational diabetes mellitus (GDM) and type 2 diabetes mellitus (T2DM) patients.

Methods A total of 61 women were selected as research objects, including GDM pregnant women in group G (n=15), healthy pregnant women in group N (n=18), T2DM patients in group D (n=14), and healthy women in group A (n=14). Four groups of fecal samples were collected and sequenced by 16S rDNA high-throughput sequencing technology. The species diversity of samples and species differences between groups were analyzed.

Results Intestinal microbiota diversity analysis showed that there were statistically significant differences in Beta diversity between the GDM pregnant women and the healthy pregnant women as well as between the T2DM patients and the healthy women (P < 0.05). In terms of Alpha diversity, the microbiota richness of T2DM patients showed significant difference compared with that of the healthy women (P < 0.05). Compared with the healthy pregnant women, the abundance of Firmicutes in the gut microbiota of the GDM pregnant women was increased, while the abundance of Bacteroidetes and Lachnobacterium were decreased, and the differences were statistically significant (P < 0.05). Compared with the healthy women, the abundance of Phascolarctobacterium in the gut microbiota of T2DM patients was increased, while the abundance of human symbiotic bacteria such as Proteobacteria, Actinobacteria, Roseburia, Turicibacter, Streptococcus, Actinomyces, Coprococcus and Proteus were decreased, and the difference was statistically significant (P < 0.05).

Conclusion Compared with the healthy women, the gut microbiota of pregnant women with GDM and T2DM patients are significantly different. The results of this study can provide a reference for the future clinical application of intestinal probiotics in the treatment of GDM and T2DM.