Quercetin Supplementation Ameliorates Myopathy Associated with Induced Type 2 Diabetes Mellitus in Rats

Abstract
Background: Myopathy is a common associated diabetic complication due to hyperglycemia and insulin resistance. Quercetin acts as reactive oxygen species' scavenger and peroxidation reactions' suppressor which causes development of diabetic complications.
Aim of Study: We investigated the possible improving effect quercetin on glycemic state, insulin resistance & skeletal muscle performance in type 2 diabetic male rats and tried to elucidate the possible underlying mechanisms.
Patients and Methods: Thirty rats were randomly divided into three groups; non-diabetic, diabetic non-treated & quer-cetin treated groups. Type 2 diabetes mellitus was induced by adding 10% fructose for 2 weeks followed by single intraperitoneal injection of streptozotocin as a consequence of hyperglycemic insulin resistance. Quercetin was given in a dose of 50mg/kg body weight orally for 4 weeks. After the end of the 4-week experimental period, fasting serum glucose, glycosylated hemoglobin, fasting serum insulin, HOMA-IR index, serum TNF-a, MDA, total antioxidant capacity, Gast wt/Tib L ratio, the strength of muscle contraction at the start and after 30min activity & glucose uptake by the muscle during 30min activity and after 30min recovery were assessed.
Results: Fructose & Streptozotocin administration signif-icantly increased fasting serum glucose, glycosylated hemo-globin (HbA1C), fasting serum insulin, HOMA IR index, confirming successful establishment of Type 2 diabetes Mel-litus model. Also increased serum MDA, TNF-a  and decreased total antioxidant capacity associated with decreased Gast wt/ Tib L ratio, decreased the strength of muscle contraction at the start and after 30min activity and reduced glucose uptake by the muscle during 30min activity and after 3 min recovery indicating occurrence of myopathy. Quercetin supplementation significantly improved the previously measured parameters compared to diabetic non-treated group.
Conclusion: Quercetin improving effect against myopathy complicating induced type 2 diabetes mellitus may be linked to its antioxidant and anti-inflammatory effect with reduced hyperglycemia and insulin resistance.