Unlocking Gut-Driven Metabolic Repair: The Role of Glucomannan Porang (<i>Amorphophallus muelleri Blume) in Insulin Resistance and Short-Chain Fatty Acid Modulation in a Type 2 Diabetes Mellitus Rat Model

Type 2 diabetes mellitus (T2DM) is characterized by impaired insulin sensitivity and alterations in gut microbial metabolites, particularly short-chain fatty acids (SCFAs). The gut microbiota contributes to energy homeostasis through metabolites involved in insulin signalling. Glucomannan porang (GMP), a prebiotic fibre native to Indonesia, may serve as a therapeutic agent by modulating gut microbiota and improving glucose regulation. This study evaluated the effects of GMP on insulin resistance and SCFAs modulation in a streptozotocin-nicotinamide (STZ-NA)-induced T2DM rat model. Thirty male Wistar rats were acclimatized for seven days, then randomly assigned to five groups: control, diabetic, Acarbose (1.8 mg/200 g BW), GMP50 (50 mg/200 g BW), and GMP100 (100 mg/200 g BW). T2DM was induced in all but the control group using STZ-NA, and induction success was validated three days later through fasting blood glucose (FBG) levels exceeding 250 mg/dL. Following validation, treatments were administered orally for 28 consecutive days. At the end of the study, blood samples were collected to measure FBG, insulin, HbA1c, HOMA-IR, GLP-1, GLUT-4, IGF-1, and SCFA profiles. GMP100 significantly reduced FBG and HbA1c (p<0.001), improved insulin sensitivity and increased GLP-1, GLUT-4, and propionic acid levels. GMP100 also significantly lowered HOMA-IR (p<0.001) and elevated IGF-1, acetate and butyrate levels, showing effects comparable to acarbose. GMP50 produced moderate, but less pronounced, improvements compared to GMP100. In conclusion, GMP at 100 mg/200 g BW effectively ameliorated insulin resistance and favourably modulated SCFA profiles in T2DM rats, suggesting its potential as an adjuvant therapy for metabolic improvement in T2DM.