Aim The present study was undertaken to measure Serum Magnesium levels in type 2 Diabetic Libyan patients as there were no studies reported to indicate the status of Mg in these patients. Materials and Methods A total of 100 Libyan patients with type 2 diabetic mellitus (48 women and 52 men) were taken for the present study from Benghazi Center for Diagnosis and Treatment of Diabetes, and 30 apparently healthy age and sex- matched individuals (15 women and 15 men) acted as control subjects. Body mass index, gender, serum magnesium, glucose and glycated hemoglobin levels were measured by standard methods and subjected to specific statistical methods of analyses. Results and Subjects The Libyan diabetics showed marked reduction in serum magnesium levels both in controlled and uncontrolled diabetic subjects compared to normal control subjects. Serum magnesium was significantly negatively correlated with duration of diabetes (r=-0.242, p=0.015), and HbA1c (r=-0.198, p=0.049). There was a near-significant negative association between magnesium and fasting blood glucose (r=-0.174, p=0.084). No significant correlation was seen between serum Mg and age, or BMI. Like other studies there was marked reduction in serum magnesium levels in diabetic Libyan subjects with significant correlation to duration of diabetes and HbA1c levels indicating that serum Mg levels may be a biomarker of duration and glycemic control in diabetic patients.