Polysaccharides, widely found in various food sources, have gained interest due to their diverse biological activities. This review critically analyzes current research on anti-diabetic polysaccharides, examining their hypoglycemic properties, signaling mechanisms, and relationships between hypoglycemic activity and structural characteristics. It also explores emerging applications of polysaccharides in hyperglycemia and diabetes treatment. Key findings show that polysaccharides' hypoglycemic mechanisms mainly involve repairing islet β-cells, regulating enzyme activity, reducing oxidative stress, alleviating inflammation, and reshaping gut microbiota. Hypoglycemic activity is mediated through one or more signaling pathways like PI3K/Akt, MAPK, cAMP-PKA, Nrf2, PKC/NF-κB, ubiquitin-proteasome, and PPARs. Additionally, the activity of dietary polysaccharides relies on their source and structural characteristics, such as monosaccharide composition, glycosidic bond types, branching degree, type of modification, and higher-order structures. Additionally, polysaccharide-based formulations, combined with chemotherapy drugs or used as nanocarriers, show significant potential in enhancing therapeutic efficacy, safety, and patient compliance of anti-diabetic drugs. This review offers valuable insights for researchers and healthcare professionals developing innovative diabetes therapies.