Diabetes is a major threat to global public health, and the numbers of diabetic patients are rapidly increasing world-wide. This study was aimed at determining the serum electrolyte concentration and glycosylated haemoglobin level of diabetic patients and apparently healthy individuals. A total of one hundred and twenty (120) subjects were used for the study. Seventy (70) subjects (apparently healthy) aged between 38 and 60 years with no history of diabetes mellitus or any other hyperglycaemic disorder served as the control group while fifty (50) subjects of both genders (38-60 years) represented those with known history of diabetes mellitus . The subjects were divided into five (5) groups. Group 1 represents diabetic subjects with genotype AA, group 2 represents non-diabetic subjects with genotype AS, group 5 represents non diabetic subjects with genotype SS, group 3 represents diabetic subjects on treatment with genotype AA while group 4 represents diabetic subjects on treatment with genotype AS. All subjects used were residents within and around the environs of Gwagwalada, Gwagwalada Area Council of the Federal Capital Territory, Abuja. The duration of the experiment was two (2) months. Blood samples from all subjects were obtained by venipuncture from the anticubital vein into plain bottles. The blood was allowed to clot and then centrifuged for 10 min at 3000 rpm. The separated serum was stored in a freezer at 2-80C till the time of use. Whole blood for determination of genotype and glycosylated haemoglobin was obtainred by venipuncture from the anticubital vein into an EDTA container. The samples were kept in the refrigerator at 2–8 0c till the time of use. The result showed a significant decrease (p<0.05) in the serum sodium ion (Na+) concentration of subjects in groups 3 and 4 representing genotype AA diabetic patients and genotype AS diabetic patients compared with the Na+ concentration of group 1 subjects (AA normal). Normal genotype SS individuals in group 5 exhibited non-significant increase (p>0.05) in the Na+ concentration compared with that of AA and AS diabetic patients on treatment in groups 3 and 4. There was significant (p<0.05) elevation of the potassium ion (K+) concentration in groups 3, 4 and 5 which represented AA diabetic subjects on treatment, AS diabetic subjects on treatment and SS normal subjects respectively compared with the K+ concentration of AA and AS normal subjects contained in groups1 and 2. The chloride ion (Cl–) concentration decreased significantly (p<0.05) in AA and AS diabetic patients on treatment compared with AA, AS and SS normal subjects. However, non-significant (p>0.05) variations were observed in the Cl– concentration of AA, AS and SS normal subjects when compared with their AA, AS diabetic subjects on treatment. Significant decrease (p<0.05) was observed in the bicarbonate ion (HCO3–) concentration of AA diabetic subjects on treatment, AS diabetic subjects on treatment and SS normal subjects compared with the HCO3– concentration of AA and AS normal subjects. The level of glycosylated hemoglobin increased significantly (p<0.05) in the AA and AS diabetic subjects on treatment compared with that of AA, AS and SS normal subjects. On the other hand, there was non-significant difference (p>0.05) in the level of glycated haemoglobin in AA, AS and SS normal subjects. It was observed from the result of the present study that the serum electrolyte (sodium, potassium, chloride and bicarbonate) and glycosylated haemoglobin concentrations showed significant difference (p<0.05) in accordance with diabetic mellitus patients irrespective of genotype. This could be utilized in the management of diabetic patients. From this study, the predictive value for glycosylated haemoglobin in diabetic patients can be said to be > 6.0 %.