The aim of the present study is to investigate oxidant / antioxidant status in type 1 and type 2 diabetic mothers and in their respective newborns to test the hypothesis that both diabetes increases maternal and fetal oxidative stress. 20 type 1, 25 type 2 diabetic and 40 healthy control mothers and their respective newborns were consecutively recruited from the Genecology and Obstetrics Department of Tlemcen hospital. The plasma total antioxidant capacity (TAC), vitamin C and glutathione, hydroperoxides, carbonyl proteins and erythrocyte antioxidant enzyme activities (catalase, superoxide dismutase) were measured in mothers and their newborns. Changes in plasma glucose and lipid levels were also determined. Type 1 and type 2 diabetic mothers had low TAC, vitamin C and glutathione values, catalase and superoxide dismutase activities, high plasma glucose, triglycerides, hydroperoxide and carbonyl protein levels as compared to control mothers. These abnormalities were worsened in type 2 diabetic mothers. Newborns of diabetic mothers also showed decreased TAC, glutathione, antioxidant enzyme activities and increased carbonyl proteins and hydroperoxides as compared to control newborns. In conclusion, diabetic mothers and their newborns are exposed to oxidative stress. Their oxidant and antioxidant status should be carefully considered and appropriate management should be organized during the pregnancy and the early postnatal period, including antioxidant supplementation.