Objective   To explore the important roles of oxidative stress in the initiation and development of type 2 diabetes mellitus induced by insulin resistance.

  Methods   By oral glucose tolerance test all enrolled subjects were divided into three groups: normal glucose tolerance(NGT), glucose intolerance(G1)and new diagnosed type 2 diabetes mellitus (T2DM).Plasma(MDA)was chosen to play a biomarker of oxidative stress, while plasma total antioxidation capability (TAOC), erythrocyte superoxide(SOD)and erythrocyte reduced glutathione(GSH)were chosen to play biomarkers of antioxidant defense system.By detecting fasting insulin levels, the insulin resistance and β-cell function were estimated with homeostasis model assessment(HOMA).

  Results   The plasma MDA levels increased significantly in T2DM individuals versus G1 individuals and NGT individuals(P < 0.001 andP < 0.001).The plasma TAOC levels decreased significantly in T2DM individuals versus G1 individuals and NGT individuals(P < 0.001 andP=0.003).The insulin resistance had significanrt difference among three groups.The index of insulin resistance(HOMAIR)was related positively to body mass index(BMI)and plasma MDA levels(P < 0.001 andP=0.003).There was an adverse relationship between homeostasis model assessment insulin resistance(HOMAIR)and plasma TAOC or erythrocyte SOD activity(P=0.017 and P=0.014).

  Conclusion   The risk factors of T2DM can induce insulin resistance by increasing the organism's oxidative stress.Oxidative stress may play key roles in the pathogenesis of type 2 diabetes mellitus.