SIRT1 and Insulin resistance: Pretreatment with hawthorn polyphenol extract (HPE) via oral administration for four weeks has regulatory effects on oxidant and inflammation agents in serum and colonic tissue and suppresses insulin resistance through inhibition of SIRT1/AMP-activated protein kinase (AMPK)/nuclear factor kappa B (NF-κB) pathway in the liver and SIRT1/NF-κB cascade in the skeletal muscles of diabetic rats model.