Yellow sweet potato enhances insulin sensitivity and reduces type 2 diabetes risk in obese rats

Abstract Background As central obesity contributes to insulin resistance and type 2 diabetes, the yellow sweet potato (Ipomoea batatas), with a lower glycemic index, higher fibre content, and lower calorie count, is a promising functional food. Objective This study aimed to evaluate the effects of a diet based on yellow sweet potatoes on biomarkers of insulin resistance in obese rats. Methods A randomized controlled design was conducted on 28 obese rats, which were allocated into four high-fat dietary groups for 3 weeks: K− (standard feed), K+ (rice-based feed), K1 (steamed yellow sweet potato), and K2 (twice-steamed yellow sweet potato). Blood samples were collected before and after the intervention, whereas tissues and caecum were collected only after intervention. Data were analyzed using SPSS, JASP, and GaphPad Prism. Results The K2 group demonstrated the most significant improvements across all measured parameters. Total antioxidant levels increased by 5.11 U/mL, while HOMA-IR and glycated albumin(%) decreased by 5.67 and 3.83, respectively. Post-prandial glucose levels also dropped significantly by 184 mg/dL. Furthermore, the K2 group exhibited the highest concentrations of GLUT4 (25.12 ng/mL), acetic acid (150.31 mmol/L), propionic acid (53.20 mmol/L), and butyric acid (27.18 mmol/L). Levels of PPAR-α and PPAR-γ were also highest in the K2 group at 1.94 ng/mL and 0.78 ng/mL, respectively. In contrast, glucose-6-phosphatase (G6P) reached its highest level in the K − group at 9.91 mIU/mL. Conclusion A twice-steamed yellow sweet potato diet significantly improved insulin sensitivity in obese rats by enhancing antioxidant capacity, GLUT4 expression, and SCFA production, while lowering insulin resistance markers. These findings support its potential as a functional food for metabolic health.