Fermentation-enriched quinoa β-glucan ameliorates disturbed gut microbiota and metabolism in type 2 diabetes mellitus mice

Quinoa β-glucan (QBG) has shown potential benefits in treating type 2 diabetes mellitus (T2DM); however, comprehensive evaluations of its effects remain limited. This study investigates the impact of QBG—derived from hot water extraction (Q-) and microbial fermentation enrichment (Q+)—on serum glucose levels, lipid profiles, appetite-regulating hormones, fecal short-chain fatty acids (SCFAs), and gut microbiota composition and function in streptozotocin/high-fat diet (STZ/HFD)-induced T2DM mice. The results indicate that QBG treatment significantly reduced fasting blood glucose, insulin levels, triglycerides (TG) and total cholesterol (TC), while concurrently increasing high-density lipoprotein cholesterol (HDL C) levels. Additionally, liver and pancreatic function improved, as evidenced by decreased levels of malondialdehyde (MDA), aspartate transaminase (AST), and alanine transaminase (ALT). SCFA levels were significantly higher in QBG-treated groups compared to MC group. QBG treatment also reduced the abundance of Firmicutes and Patescibacteria, along with the Firmicutes/Bacteroidota ratio, while increasing levels of Bacteroidota and Actinobacteria. These findings suggest that QBG can regulate the dysbiosis of SCFAs production in T2DM mice and may indirectly modulate the secretion of appetite-regulating hormones by influencing gut microbiota composition. Furthermore, PICRUSt analysis revealed that QBG treatment, particularly Q + _H, could enhance disrupted metabolism and improve gut microbiota functions, helping restore normal physiological function.