The Korean Diabetes Association and the Korean Society of Nephrology have agreed on the criteria for using metformin on patients with type 2 diabetes mellitus (T2DM) and chronic kidney disease (CKD).

At a recent joint symposium, the two medical academies said the consensus would notably help patients undergo imaging studies using iodinated contrast media (ICM).

CKD is a global public health problem, and its prevalence is gradually increasing, mainly due to an increase in the number of patients with T2DM. CKD develops in approximately 35 percent of patients with T2DM and is associated with increased mortality

Until now, the safety of metformin use for patients with T2DM and CKD was controversial, and more recent guidelines have suggested physicians use metformin cautiously in this group until more definitive evidence concerning its safety is available. The consensus, published by the two societies, will allow metformin usage when the estimated glomerular filtration rate (eGFR) is ≥45 mL/min/1.73m2.

However, if the eGFR is between 30 and 44 mL/min/1.73m2, the guideline stated that doctors should not use metformin treatment, and, if metformin is already in use, they should administer a daily dose of ≤1,000 mg.

Also, patients whose eGFR has fallen below 30mL/min should discontinue metformin administration.

In the case of prescribing metformin to patients who plan to undergo ICM-related procedures, the guideline stated that a pre-evaluation on the patient's renal functions should be conducted beforehand.

The guideline added that any decision on using ICM and stopping metformin should be based on renal function test results.

Currently, hospitals recommend metformin as the primary drug used primarily to lower blood sugar in the field of type 2 diabetes.

However, the problem is that in patients with renal dysfunction, a question arises as to whether or not to continue administration during imaging studies using ICM.

Until now, major domestic and foreign diabetes guidelines have contraindicated the use of metformin medication in personnel with renal impairment due to concerns about the occurrence of lactic acidosis.

Notably, in the case of clinically significant nephrotoxicity caused by the use of ICM, the guidelines recommend refraining from taking metformin in high-risk groups with complications.

However, this situation has changed considerably following recent epidemiological studies that showed the risk of lactic acidosis associated with metformin use was not greater than that of other antidiabetic medications, and that metformin use in patients with diabetes mellitus and heart failure did not necessarily increase the risk of lactic acidosis

According to the new guidelines, doctors will now discontinue metformin in patients with a high risk of contrast-induced acute kidney injury (CI-AKI) who are taking metformin that plan to undergo CT imaging using a contrast agent

Notably, during procedures involving intravenous administration of ICM, metformin should be discontinued starting the day of the procedures and up to 48 hours post-procedures, if the eGFR is <60 mL/min/1.73m2.

However, the treatment direction is different in patients who do not belong to the high-risk group. For patients who are not at high risk for CI-AKI, eGFR above 60mL/min, the guideline state that it is not necessary to stop metformin treatment before or after administration of contrast agents.

The results of the research were published in the Diabetes & Metabolism Journal, under the title "Metformin Treatment for Patients with Diabetes and Chronic Kidney Disease: A Korean Diabetes Association and Korean Society of Nephrology Consensus Statement."

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