Abstract
BackgroundMetformin associated lactic acidosis (MALA) is a rare but lethal complication. There is no consensus regarding when to stop and resume metformin in patients who undergo coronary artery bypass grafting (CABG). This study aimed to determine if uninterrupted metformin administration in patients with diabetes undergoing CABG increases the risk of lactic acidosis.MethodsOver a span of 12 months (2015–2016), 127 patients with type 2 diabetes underwent isolated CABG. Of those, 41 patients (32%) continued taking metformin and 86 patients (68%) took other antidiabetic agents. Patients taking metformin took the drug until the day of surgery and resumed taking it 3 h after extubation.ResultsThere were no differences in clinical outcomes or complications between groups. Serial measurement of cardiac, liver, and kidney biomarkers were similar between groups. The mean peak lactic acid level was significantly higher in the non-metformin users (5.4 ± 2.6 vs. 7.4 ± 4.1 mmol/l; P = 0.001). Multivariable logistic regression analysis identified the need for vasopressor administration as an independent predictor of lactic acidosis (odds ratio: 7.3, 95% confidence interval: 2.5–20.6; P < 0.001).ConclusionIn the absence of risk factors associated with persistent lactic acidosis, such as shock or acute kidney or liver injury, continued peri-operative metformin administration was not associated with the occurrence of lactic acidosis in patients undergoing CABG. Elevated lactic acid levels seem to be directly related to tissue anoxia caused by escalating vasopressor support after surgery.
Highlights
Metformin associated lactic acidosis (MALA) is a rare but lethal complication
The objective of this study was to determine whether continuing perioperative metformin administration in patients with diabetes during coronary artery bypass grafting (CABG) leads to significant lactate accumulation when compared to patients with diabetes who are not treated with metformin
In a systemic review by Salpeter et al [4] evaluating pooled data from 347 comparative trials comparing the incidence of lactic acidosis in patients with diabetes who took metformin versus those who did not, a lower incidence of lactic acidosis was found in the metformin group (0.0043% vs. 0.0054%)
Summary
Metformin associated lactic acidosis (MALA) is a rare but lethal complication. There is no consensus regarding when to stop and resume metformin in patients who undergo coronary artery bypass grafting (CABG). This study aimed to determine if uninterrupted metformin administration in patients with diabetes undergoing CABG increases the risk of lactic acidosis. Belonging to the biguanide group of hypoglycemics, metformin mainly acts by suppressing gluconeogenesis in the liver, decreasing glucose absorption in the digestive tract, and increasing muscle and fatty tissue sensitivity to insulin [1]. Metformin associated lactic acidosis (MALA) is a rare but fatal condition with a reported incidence of. There are no existing safety guidelines concerning metformin administration during the perioperative period in patients scheduled for surgery.
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