Taking into account that combination therapy of current antidiabetic agents with natural antioxidants having beneficial effects on diabetic disturbances might be an interesting strategy, the present study showed the additive effects of curcumin combined with metformin on decreasing dyslipidemia and glycoxidative stress in diabetic rats, in association with the maintenance of metformin effects on decreasing glycemia and the curcumin effects on increasing PON 1 activity. This evidence concerns the gene PON1 and metabolic syndrome.