Objective:To observe the clinical effect of berberine hydrochloride tablets combined with metformin in the treatment of primary type 2 diabetes. MethodsA total of 192 patients with primary type 2 diabetes were randomly divided into treatment group and control group, 96 cases in each group; the control group was treated with metformin, and the treatment group was treated with berberine hydrochloride tablets and metformin. The course of treatment in both groups was 6 months. The changes of blood glucose (FBG, 2 hPPG, HbA1c), blood lipid (TC, LDL-C), BMI, oxidative stress products (8-OHdG, MDA, SOD), and immune cytokines (TNF-α, IL-6) were observed and the correlation between HbA1c and oxidative stress products (8-OHdG, MDA, SOD), immune cytokines (TNF-α, IL-6) was analyzed.  Results:After treatment, the levels of FBG, 2 hPPG, HbA1c, TC, LDL-C, BMI, 8-OHdG, MDA, TNF-α, IL-6 significantly decreased (P<0.05) and the level of SOD significantly increased (P<0.05) in both groups; after treatment, all indexes in the treatment group improved more significantly than those in the control group (P<0.05), and 8-OHdG was positively correlated with HbA1c.  Conclusion:Berberine hydrochloride tablets combined with metformin can effectively reduce the blood glucose, blood lipid, body mass, oxidative stress and inflammatory response in patients with primary type 2 diabetes, and 8-OHdG may be an evaluation index for the prognosis of type 2 diabetes mellitus.