Interactions between structure and function of resistant glucans for alleviating type 2 diabetes mellitus (T2DM) and its complications in mice

Resistant glucan, a functional dietary fiber, has been shown to alleviate type 2 diabetes mellitus (T2DM) and its complications in clinical studies. However, the interactions between the special structure of resistant glucan and the metabolism-related pathways in T2DM have not yet been systematically studied. This study identified the structural differences between resistant glucans prepared by new and old methods. Oral gavage with two resistant glucans in T2DM mice, led to significant improvements in glucose and lipid metabolism as measured by related indicators (including gut microbiota, fecal metabolites, and physiological and biochemical indexes). According to these results, in addition to van der Waals forces, micelle formation, and hydrogen bonding, the branching structures of resistant glucans produced more hydroxyl, carbonyl, and keto groups that linked cholesterols, cholesterol esters, and low-density lipoprotein intermediates. Moreover, after lipid clearing, the metabolic environment was more conducive to the proliferation of specific gut microbiota (including Phascolarctobacterium, Prevotella, Butyricicoccus, Weissella, and Anaerostipes) with decreasing abundance ratios of Firmicutes and Bacteroides. This facilitated the synthesis of high-density lipoprotein, conversion of cholesterol into coprostanol, and production of short-chain fatty acids and bile acids. Our findings provide a foundation for comprehensive investigation of the structure of resistant glucan in the promotion and prevention of T2DM.