Significance of lactic acid accumulation after exposure to iodinated contrast media in diabetic patients receiving metformin

Abstract

Metformin is a biguanide oral hypoglycemic agent with cardio protective effect. Lactic acidosis is a rare fatal adverse effect of metformin (0.01–0.15 per 1000 patients). Administration of intravenous iodinated contrast media during radiologic procedures may lead to acute decline in renal function (0.1–13%) and subsequent lactic acidosis in patients receiving metformin therapy. No clinical trials tested the extent of lactic acidosis in diabetic patients exposed to contrast media. This study aimed to investigate the correlation of lactic acid accumulation with clinical outcome in metformin treated diabetic patients exposed to contrast media. A single-center, prospective single arm clinical observational trial involved diabetic patients on metformin therapy undergoing cardiac catheterization. The study endpoints are drawn from laboratory and clinical outcomes. Patients with acute renal dysfunction or deterioration were excluded from the study. The patients were followed at baseline, and 72 h for clinical and laboratory assessment. The primary end point was clinically significant lactic acidosis. 156 diabetic patients on metformin were enrolled in this study with mean age of 61.8 ± 10.4, 84% were males. Lactic acid, bicarbonate, and pH levels, at baseline and 72 h were; (1.7 ± 1.2 & 2.1 ± 1.8, p value = 0.016), (24.4 ± 2.0 & 24.6 ± 3.2, p = 0.7), and (7.37 ± 0.05 & 7.36 ± 0.06, p = 0.44), respectively. All patients were clinically stable at 3 days follow up, no reported death or significant adverse events duringthe study period. In contrast to the current recommendations, continuing use of metformin duringcontrast exposure in high risk population was found to be safe and not associated with clinically significant lactic acidosis.