Polysaccharides from small black soybean alleviating type 2 diabetes via modulation of gut microbiota and serum metabolism

Type 2 diabetes (T2DM) is a complex metabolic disorder associated with chronic high blood sugar and insulin resistance. Small black soybean, as a medicinal soybean, is used for tonifying kidney and spleen in traditional Chinese medicine. We performed the antidiabtic effect and mechanism of crude polysaccharides extracted from small black soybean (SB) by gut microbiota and metabolic modulation in STZ-induced diabetic rats. It is found that SB improved symptoms of hyperglycemia and hyperlipidemia and regulated linoleic acid metabolism. In addition, the relative abundance of Ruminococcus, Oscillospira, Dorea and Mucispirillum were modified by the middle dose of SB and these bacterial genera showed strong association with 6 vital metabolites and 10 risk indicators of T2DM. Additionally, it is further showed that 400 mg/kg pure polysaccharides exhibited more favorable antidiabetic activity than crude polysaccharides, which suggest that the antidiabetic effect of small black bean polysaccharides attributes to the pure polysaccharides.