The gut microbiota of non-obese Japanese pregnant women with gestational diabetes mellitus.

Recent evidence has shown that gut microbiota dysbiosis is associated with development of gestational diabetes mellitus (GDM). However, the gut microbiota composition of non-obese women with GDM, which accounts for a relatively large percentage of Asian GDM, is unknown. We investigated the characteristics of gut microbiota of Japanese pregnant women with GDM. Fecal samples from Japanese pregnant women with GDM (n=20) and normal glucose tolerance (NGT, n=16) were collected at the time of GDM diagnosis (T1), at 35-37 weeks of gestation (T2), and at 4 weeks postpartum (T3). Gut microbiota composition was characterized from fecal DNA by sequencing of 16S rRNA genes. Serum samples were collected late in the third trimester, and the circulating levels of adiponectin and IL-6 were measured by ELISA. At the genus level, Peptostreptococcaceae Romboutsia was enriched in GDM women at T1 (p=0.008) and T2 (p=0.047). The women with lower serum adiponectin tended to have more Romboutsia. The Shannon index was significantly lower in the GDM women at T3 than in the NGT women (p=0.008), and that of the GDM women decreased significantly from T2 to T3 (p=0.02). No significant difference in bacterial community structure was found in a beta diversity analysis. The non-obese GDM women (body mass index <25.0 kg/m²) showed a lower abundance of Coriobacteriaceae Collinsella at T1 (p=0.03) and higher abundance of Akkermansia at T2 (p=0.04) than the normal control. The non-obese GDM women had the distinctive gut microbiota profiles. Analysis of gut microbiota is potentially useful for risk assessment of GDM in non-obese pregnant women.