# Systematic review and meta-analysis of current guidelines, and their evidence base, on risk of renal function after administration of contrast medium for diabetic patients receiving metformin

## TL;DR

This study found that continuing metformin in diabetic patients during contrast agent use does not increase kidney or metabolic risks.

## Contribution

A meta-analysis of guidelines and evidence on metformin use during contrast administration in diabetic patients.

## Key findings

- Continuing metformin does not increase contrast-induced acute kidney injury or metabolic acidosis risk.
- Metformin may be associated with a modest reduction in serum creatinine after contrast exposure.
- Contrast volume is a consistent predictor of acute kidney injury.

## Abstract

Our study aimed to determine through a meta-analysis whether continuing metformin use in diabetic patients receiving contrast agents would increase the risk of renal impairment and metabolic abnormalities.

We searched the PubMed, EBSCO, Medline, and the Cochrane Central Register of Controlled Trials from the inception dates to March 2024. The included studies comparing metformin users and non-users during contrast agent administration in diabetic patients. Outcome measures included contrast-induced acute kidney injury (CI-AKI), serum creatinine, estimated glomerular filtration rate (eGFR), lactate level, and incidence of metabolic acidosis. We used odds ratio (OR) for dichotomous outcomes and weighted or standardized mean difference (WMD or SMD) for continuous outcomes, depending on scale consistency across studies.

Analysis involved 2 randomized controlled trials and 5 retrospective cohorts comprising 2020 patients. There were no significant differences between the metformin and non-metformin groups in CI-AKI incidence (OR: 0.87, 95% CI: 0.63–1.20), changes in renal function (serum creatinine: SMD: −0.15, 95% CI: −0.64–0.35; eGFR: WMD: 3.35, 95% CI: −1.60–8.29), incidence of metabolic acidosis (OR: 0.90, 95% CI: 0.57–1.43), and lactate levels (SMD: 0.29, 95% CI: −0.53–1.11). Sensitivity analysis excluding one study revealed a significant reduction in creatinine with metformin. Logistic regression meta-analysis showed that metformin use was not significantly associated with CI-AKI or metabolic acidosis, while contrast volume was the only consistent predictor of CI-AKI. Lower baseline CO2 was independently associated with increased risk of metabolic acidosis.

Our analysis indicates that continuing metformin during contrast agent administration does not increase the risk of CI-AKI, acidosis, or eGFR compared to discontinuation or non-use of metformin. Additionally, continuation of metformin may be associated with a modest reduction in serum creatinine levels after contrast exposure. However, the limited quality of included studies may weaken the strength of these conclusions.

https://www.crd.york.ac.uk/PROSPERO/view/CRD42023459602, identifier: CRD42023459602.