Effect and mechanism of insoluble dietary fiber on postprandial blood sugar regulation

High oil and sugar diets that lack dietary fiber affect human health and increase the risk of chronic diseases, such as type 2 diabetes. In recent decades, researchers globally have shown tremendous interest in evaluating the relationship between insoluble dietary fiber (IDF) and diabetes. IDF, a non-starch polysaccharide, effectively regulates blood sugar, glucose adsorption, enzyme activity inhibition, fermentation, antioxidants, and anti-inflammatory properties. This review primarily focuses on the action effect and mechanism of IDF in blood sugar regulation, as well as the effect of IDF modification on its hypoglycemic properties based on studies conducted in the last decade, and discusses the application of IDF in food. IDF can be used to prevent type 2 diabetes through its beneficial functional and physicochemical properties. First, because of its loose structure and large surface area, IDF can adsorb glucose and enzyme molecules to inhibit excessive glucose adsorption. Second, the gut microbiota can ferment IDF to produce short-chain fatty acids (SCFAs) that regulate the body's metabolism and thus blood sugar levels. Third, IDF and bound polyphenols can bind to enzyme molecules to decrease starch hydrolysis, thus, regulate blood sugar levels. Furthermore, IDF and bound polyphenols can remove excess reactive oxygen species and reduce oxidative stress, thereby improving hyperglycemia. This review offers a theoretical basis for IDF as a dietary supplement for managing type 2 diabetes.