: Probiotics have recently emerged as promising agents in the prevention and treatment of various human diseases. This study investigates the therapeutic potential of SA9 in the management of type 2 diabetes mellitus (T2DM). : The in vitro antidiabetic activity of SA9 was primarily assessed via its α-glucosidase inhibitory capacity, complemented by metabolomic profiling to identify putative bioactive metabolites. The antidiabetic efficacy was further evaluated in a db/db mouse model, focusing on glucose tolerance, inflammatory biomarkers, and gut microbiota composition. : SA9 showed significant inhibitory effects on α-glucosidase and α-amylase, and DNJ and other active substances were detected in its culture supernatant. After 6 weeks of continuous administration, the fasting blood glucose level, glucose tolerance, and inflammation indexes of mice were significantly improved. Beneficial changes in the structure of the intestinal flora occurred after the probiotic intervention, as evidenced by a significant decrease in harmful bacteria (e.g., ) and a significant enrichment of beneficial bacteria (e.g., ). : SA9 exerts robust antidiabetic effects and holds promise as a novel strategy for the prevention and management of T2DM.