Type 2 Diabetes mellitus T2DM has been suggested to be the most common metabolic disorder associated with magnesium deficiency which has many adverse outcomes. The aim of this study was to evaluate plasma Mg in 126 T2DM patients recruited from Diabetes Centre in Lattakia, compare them to 70 healthy individuals, and assess the correlation between plasma Mg and HbA1c as a glycemic control biomarker. Magnesium was measured using xylidyl blue colorimetric method. HbA1c was measured using ion-exchange resin separation. The SPSS 19.0 software was used for statistical analysis. Mean plasma Mg concentrations of the diabetics was significantly lower than controls (P=0.0001). Plasma magnesium was negatively correlated with HbA1c (r=-0.5, P=0.0002). Plasma magnesium was below the normal reference range (1.9-2.5 mg/dL) in 47.6% of diabetics and 28.6% of controls. In conclusion, it is important to monitor Mg levels in both T2DM patients and non-diabetics and take procedures to correct hypomagnesaemia states.