Introduction & Objective: In the context effect of metformin in patients with acute coronary syndrome, available evidence supports cardiac effect. Yet, there is doubt about continuation or discontinuation of metformin before major surgery. The aim of the present study is to determine the efficacy of continuing metformin in plasma glucose, renal function index, arterial PH in type II diabetic patients after coronary artery bypass graft surgery.    

Materials & Methods: In this clinical-experimental study, 90 type II diabetic patients with ASA class II admitted for CABG surgery in Hamadan Ekbatan Hospital were enrolled  in the study in 2014 and were randomly assigned to two groups , one group treated with insulin and continued metformin and the other group treated with insulin and discontinued metformin.In the beginning indicators such as age, sex, body mass index (BMI) were compared which were not significantly different in the two groups. Then, other parameters such as blood glucose, BUN, Cr, arterial blood PH, cardiac arrhythmia and need for inotrope were compared. Used inotropes in this study included dopamine, dobutamine, epinephrine, norepinephrine, milrinon to achieve  systolic blood presser pressure over 100mmHg.

Results: Average plasma BUN after surgery and one day after surgery in the group who discontinued metformin significantly were higher compared with the metformin group, but no differences were observed in average plasma BUN in  the 2nd and 3rd days after surgery in the two groups. During 3 days after surgery, average plasma creatinine was significantly lower in metformin group compared to non- metformin group. Although there was  no difference between the  two groups in pH parameter before surgery but in the metformin group, average pH was lower than non-metformin group after surgery. Before and 3 days after surgery mean blood glucose level was not significantly different between the two groups. During surgery, average need for inotrope in metformin group equaled 1.57 person and in non- metformin group equaled 1.05 person showing no significant difference in demography. In the both groups, not only before surgery, but also after surgery there was no cardiac arrhythmia. Also, the need for inotrope duration and tracheal intubation duration in ICU were not significantly different.

Conclusion: Although serum glucose level of patients did not change, continuation and discontinuation of metformin in patients with CABG surgery was concomitant with elevated BUN and Cr. Level and decrease of pH on the 1st and 2nd days after surgery. Noticeably, BUN and Cr. Fluctuation in patients who continued metformin, were significantly lower, but  in the two groups these  values were  reversible and return to normal range in pending several days after surgery. Prescription of this drug did not increase the need for cardiac inotrope and risk of incidence of arrhythmia after surgery.