Preparation of Platycodin D Microspheres and Their Protective Effects on Type 2 Diabetes Mellitus

The treatment of type 2 diabetes (T2DM) faces numerous challenges. Oral insulin (Ins) and other short-acting compounds still encounter significant obstacles in the hostile gastrointestinal environment, including low bioavailability and rapid metabolic clearance. Platycodin D (PD) is a natural compound with demonstrated hypoglycemic and lipid-lowering effects. In this study, PD was encapsulated using alginate to prepare orally administrable, pH-responsive, gut-targeted gel microspheres (PD@MPs), and their efficacy in improving T2DM prognosis was investigated. In vitro release studies demonstrated that PD@MPs avoided degradation by gastric acid and were released in the intestine. Cell experiments indicated that PD possessed significant antioxidant and anti-apoptotic properties. Masson, immunohistochemistry, and immunofluorescence staining revealed that PD@MPs alleviated inflammation in key metabolic organs and maintained normal pancreatic tissue function and morphology. Western blot analysis assessed the expression of proteins related to hepatic glycogen synthesis, including IRS-1, GLUT2, GSK-3β, and AKT. The research results indicate that the assembly strategy using sodium alginate (SA) as the coating layer has enabled the oral administration of PD and has demonstrated its potential in the treatment of diabetes.