In subjects with impaired insulin action, alterations of the serum sodium and potassium concentrations have been reported. The resulting cationic imbalance, along with the osmotic effect of the elevated sugar levels, could influence the course of diabetes mellitus management. Therefore, this study was conducted to compare the fasting blood glucose and HbA1c levels with those of the serum electrolytes. Blood samples were collected for assessment of HbA1c, fasting blood glucose (FBS), and electrolytes using different automated methods. A significant association between the serum sodium and FBS levels among types 1 and 2 insulin-treated patients, and type 2 oral agent patients was observed. A total of 138 diabetic subjects were randomly selected from any gender aged between 25 and 65 years at the University Diabetes Center, King Saud University, Riyadh KSA. The subjects were classified into types 1 or 2 DM using ADA criteria. Blood samples were collected for assessment of HbA1c, FBS, and electrolytes using different automated methods. It showed a significant association between serum sodium, FBS among type 1, type 2 insulin treated, and type 2 oral agent groups. However, the association of sodium and HbA1c was insignificant when analyzed individually. A statistically significant association (P < 0.001) was observed between the levels of serum sodium and the fasting blood glucose levels. This study demonstrated significant reduction in serum sodium level among types 1 or 2 diabetic patients especially among insulin-treated patients. No significant association was demonstrated by serum potassium with FBS and degree of diabetes control.