The study was aimed at comparing the concentration of metabolic parameters, the serum concentration of oxidized low density lipoproteins (oxLDL) and the activity of platelet activating factor acetylhydrolase (PAF-AH) in the relation to the serum concentration of magnesium (Mg) in patients with type 1 diabetes (DM1). DM1 patients (n=78) were divided into 2 groups: patients with low serum Mg concentration (<0.7 mmol/L, group 1, n=34) and patients with reference levels of Mg (>or=0.7 mmol/L, group 2, n=44). A control group (n=24) of healthy subjects was also recruited. Our results showed that DM1 patients had lower serum Mg concentrations than the control group. It was found that parameters of poor metabolic control and lipid profile are not related to the serum Mg concentration in DM1 patients. However, both the Mg concentration and the PAF-AH activity are independently related to the serum oxLDL concentration. In group 1 the oxLDL concentration and the PAF-AH activity were higher than in group 2, and the control group. Two groups of DM1 patients did not show any differences with regard to the metabolic control. Therefore, the oxidative modification of LDL and the higher activity of PAF-AH are related with the low Mg status; however, no relation has been observed between these parameters and the poor metabolic control in DM1 patients.