The association between metformin use and contrast-induced nephropathy in diabetic patients undergoing coronary angiography

Aims: Contrast-induced nephropathy (CIN) is a significant cause of hospital-acquired acute kidney injury, particularly in patients with diabetes mellitus undergoing coronary angiography. Although metformin is a widely prescribed antidiabetic agent, its role in CIN prevention remains controversial. This study aimed to investigate the impact of metformin use on the development of CIN in diabetic patients undergoing coronary angiography. Methods: This retrospective cohort study included 398 diabetic patients undergoing coronary angiography with a diagnosis of acute coronary syndrome between November 2022 and December 2024. Patients were classified into two groups based on metformin use (metformin group, n=122; non-metformin group, n=276). CIN was defined as a ≥25% or ≥0.5 mg/dl increase in serum creatinine within 48 hours post-procedure. Demographic, clinical, laboratory, and procedural data were analyzed. Multivariate logistic regression was used to identify independent predictors of CIN. Results: CIN occurred in 6.6% of patients in the metformin group and 20.3% in the non-metformin group (p=0.001). Metformin use was independently associated with a lower risk of CIN (OR: 0.31; 95% CI: 0.14–0.69; p=0.004) in the multivariate logistic regression analysis. Other independent predictors of CIN included age >65 years, chronic kidney disease, high glucose, hemoglobin, CRP, smoking, and contrast volume. Conclusion: Metformin use is does not increase the risk of CIN in diabetic patients undergoing coronary angiography. These findings support the potential renoprotective effect of metformin and question the necessity of routinely discontinuing it before contrast administration in patients with preserved renal function.