Abstract: Background: Type 2 diabetes (T2DM) has been associated with deficiencies in serum magnesium level, decreasing insulin sensitivity and glucose metabolism. Glycosylated hemoglobin (Hb1Ac) is a biomarker of glucose values within the half-life of the erythrocyte, that is, 3 months. Low circulating and intracellular magnesium levels can modify glucose metabolism and insulin sensitivity. Renal solute management is a parameter little used to estimate circulating and excreted concentrations of elements such as magnesium. Objective: The purpose of this study was to assess and associated fractional excretion of magnesium (FEMg) and serum magnesium with metabolic parameters, especially Hb1Ac percent, in a group of well characterized subjects with T2DM and non-diabetics subjects (ND). Methods: According to Hb1Ac, two groups were compared and associated with existing biochemical parameters, included Hb1Ac, fasting glucose, lipid profile, serum creatinine, serum magnesium and urinary creatinine for FEMg. Results: HbA1c levels were explained by serum magnesium in 25%. Serum magnesium levels in the ND group were higher than in the T2DM group and this was a statistically significant difference. Serum magnesium ≤1.8 is a risk factor (OD 16.1; P=0.021) for an HbA1c ≥ 6.5%. Conclusion: In this study, hypomagnesemia was a parameter strongly associated with the diagnosis and progression of T2DM, while FEMg showed no significant association.