Background: Cardiopulmonary bypass (CPB) during coronary artery bypass grafting is thought to contribute significantly to increased blood glucose level and altered blood electrolytes balance during the operation. In this (CABG) study, blood electrolytes and glucose during CPB in insulin-dependent diabetic and non-diabetic patients were assessed with special emphasis on the trend of the changes. Materials and Methods: Blood glucose and electrolytes were assessed in 30 insulin-dependent diabetic and 30 non-diabetic patients, classified as class II and III American Society of Anesthesiologist, before, during, and after CPB. Repeated-measures analysis of variance (ANOVA) was used to compare the trend of the changes during CPB for the two groups. Results: The trend in blood glucose level did not show any significant difference between two groups ( P = 0.59). For other blood factors, no significant between-group difference was detected except for PaCO 2 ( P = 0.002). Conclusion: The study suggested that the changes in blood electrolytes and the increase in blood glucose level do not differ between insulin dependent diabetic and non-diabetic patients.