The association between use of metformin and change in serum CO2 level after administration of contrast medium

•The use of metformin was not associated with metabolic acidosis after contrast exposure.•The coexisting risk factors for metabolic acidosis were present in patient with metabolic acidosis after contrast exposure.•There is a need to consider the maintenance of metformin during a CT scan in patients with a low risk for lactic acidosis.

AimTo evaluate the changes in serum creatinine and total CO2 levels in patients receiving metformin during administration of contrast medium.Materials and methodsPatient records from January 2012 to December 2012 after the administration of contrast medium were reviewed retrospectively. A total of 924 patients were included for the final analysis. Of them, 105 received metformin during contrast medium administration, 112 were taking other oral hypoglycaemic agents, and 707 patients were not diabetic (controls).ResultsNo significant change in total CO2 levels was detected (p=0.678). Metabolic acidosis was present in 33 (31.4%) metformin users, 31 (28.6%) other oral hypoglycaemic agent users, and 153 (21.6%) control patients. In the present logistic regression analysis, age, baseline levels of creatinine, and total CO2 levels were associated with metabolic acidosis after contrast medium exposure.ConclusionThese data indicate the presence of a coexisting risk factor, other than metformin use, associated with metabolic acidosis after contrast medium exposure. No relationship was found between the use of metformin and metabolic acidosis during contrast medium exposure.