Protective Effects of Polygonatum sibiricum Polysaccharides Against Type 2 Diabetic Mice Induced by High-Fat Diet and Low-Dose Streptozotocin

Polysaccharides possessing hypoglycemic effects have shown promising results in treating diabetes. Polygonatum sibiricum polysaccharide (PSP) is one of the most active ingredients in the Chinese medicine P. sibiricum Redoute with many biological activities. However, its efficacy in alleviating type 2 diabetes mellitus (T2DM) remains unexplored. Our aim is to evaluate the protective effect of PSP against T2DM by measuring body weight and serum biochemical indicators, examining the histopathological images of pancreatic and liver tissues, detecting fecal short-chain fatty acid (SCFA) content, and analyzing the intestinal flora diversity and the microbiota structure in T2DM mice. The findings indicated that PSP treatment in T2DM mice could obviously decrease the fasting blood glucose and fasting insulin levels, ameliorate glucose tolerance, insulin resistance, lipid, and inflammatory factor levels, attenuate pancreatic and liver damage, and increase the fecal SCFA content. In addition, PSP could modulate the composition of gut microbiota in T2DM mice, resulting in the relative abundance of Firmicutes decreasing and that of Bacteroidetes increasing, along with the abundance of beneficial flora significantly increasing, especially SCFA-producing bacteria. The findings indicate that PSP administration protected against diabetes by controlling disordered glucolipid metabolism and modulating the gut microbiota, which provides a valuable strategy for the utilization of PSP to treat T2DM.