Evaluation of the Effect of Metformin and Insulin in Hyperglycemia Treatment after Coronary Artery Bypass Surgery in Nondiabetic Patients

INTRODUCTION: Insulin therapy is the most commonly used treatment for controlling hyperglycemia after coronary artery bypass surgery in both diabetic and nondiabetic patients. Metformin has been indicated for critically ill patients as an alternate for the treatment of hyperglycemia. This study evaluated the effect of metformin and insulin in hyperglycemia treatment after coronary artery bypass surgery in nondiabetic patients. SETTINGS AND DESIGN: This study was a clinical trial comprising nondiabetic patients who had undergone coronary artery bypass surgery. Patients were randomly divided into the insulin group and the metformin group. METHODS: Patients in the insulin group received continuous infusion of insulin while those in the metformin group received 500 mg metformin tablets twice daily. All the patients were followed up for 3 days after stabilization of blood glucose levels. STATISTICAL ANALYSIS: Data were analyzed using Chi-square test and Mann–Whitney U-test. RESULTS: This study included a total of 56 patients. During the study period, the mean blood glucose levels decreased from 225.24 to 112.36 mg/dl (↓112.88 mg/dl) in the insulin group and from 221.80 to 121.92 mg/dl in the metformin group (↓99.88 mg/dl). There was no significant difference in the blood glucose levels of the patients between the two groups at any measurement times (P > 0.05). CONCLUSION: Using 500 mg metformin twice daily is similar to using insulin in nondiabetic patients undergoing coronary artery bypass graft. Therefore, the use of metformin can be considered as a treatment strategy for controlling hyperglycemia in this group of patients.