Hypoglycemic Effect of Sago Starch and Red Bean Flour-based Analogue Rice on Diabetic Rats with STZ-NA Induction

Resistant starch is known to reduce blood glucose levels. Analogue rice formulated from sago starch and red bean flour has been reported to contain high levels of resistant starch. This study evaluated the hypoglycemic effects and mechanisms of such rice in diabetic rats induced by streptozotocin-nicotinamide (STZ-NA). Thirty-five male Wistar rats were divided into five groups with specific diets: a healthy control group (KS) fed standard feed, and diabetic groups fed standard feed (DSTD), boiled rice (DBMW), 100% sago starch-based analogue rice (DBS), or 90% sago starch and 10% red bean flour-based analogue rice (DBSKM). Interventions lasted 4 weeks, with weekly monitoring of blood glucose levels, biweekly assessment of insulin resistance via the HOMA-IR index, and final analysis of short-chain fatty acid (SCFA) concentrations in cecal digesta. An in-vitro glucose absorption assay using an inverted ileo-anal pouch was also conducted. The DBS group achieved the greatest blood glucose reduction (56%), while DBSKM showed the most significant improvement in insulin resistance, reducing the HOMA-IR index by 81%. Conversely, the DSTD group exhibited a 10% increase in the index. SCFA concentrations were higher (P < 0.05) in DBS (133 mmol/L) and DBSKM (95 mmol/L) than DBMW (61 mmol/L). Glucose absorbability was significantly lower in DBS (13%) and DBSKM (16%) than DBMW (56%) (P < 0.05). These findings indicate that the hypoglycemic effects and improved insulin sensitivity in rats fed the analogue rice were associated with increased SCFA production and reduced glucose absorption, likely due to the rice’s high resistant starch content.