Dietary flavonoids are abundant in natural plants and possess multiple pharmacological and nutritional activities. In this study, apigenin, luteolin, and baicalein were chosen to evaluate their anti-diabetic effect in high-glucose and dexamethasone induced insulin-resistant (IR) HepG2 cells. All flavonoids improves the glucose consumption and glycogen synthesis abilities in IR-HepG2 cells via activating glucose transporter protein 4 (GLUT4) and phosphor-glycogen synthase kinase (GSK-3β). These flavonoids significantly inhibited the production of reactive oxygen species (ROS) and advanced glycation end-products (AGEs), which were closely related to the suppression of the phosphorylation form of NF-κB and P65. The expression levels of insulin receptor substrate-1 (IRS-1), insulin receptor substrate-2 (IRS-2) and phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) pathway in IR-HepG2 cells were all partially activated by the flavonoids, with variable effects. Furthermore, the intracellular metabolic conditions of the flavonoids were also evaluated.