Preventive and Therapeutic Efficacy of Roselle Beverage Residue in Late-Stage Type 2 Diabetic Rats

The residue from roselle beverage production is rich in polyphenols and dietary fiber. We investigated its potential as a preventive and therapeutic agent for type 2 diabetes mellitus (T2DM). Male Wistar rats were fed a high-fat high-fructose diet (HFFD) for 17 weeks, reaching insulin resistance by week 9, and induced to T2DM with streptozotocin (STZ) at week 13. Roselle beverage residue (RBR) was administered ad libitum mixed at 6% with the HFFD. Rats received HFFD+RBR as a preventive strategy starting at week 1 (healthy) and week 9 (insulin resistant), whereas the treatment strategy in T2DM rats started at week 14 alone or in combination with metformin (200 mg/kg/day), with a control metformin-treated group. All RBR-supplemented groups showed reduced serum glucose levels (1.4-fold to 1.8-fold) compared with the HFFD+STZ control group. Preventive RBR administration enhanced pancreatic function, leading to improved insulin sensitivity (6.5-fold to 7.9-fold). Gene expression analysis identified slight alterations in hepatic and skeletal muscle glucose metabolism. Additionally, RBR supplementation demonstrated a preventive role in mitigating hyperuricemia (2.1-fold to 2.2-fold), with no effect on glomerular hyperfiltration. While the exact mechanisms underlying RBR effects remain to be fully elucidated, our findings highlight its promising potential as a dietary supplement for preventing and treating T2DM.