Background <p>Identification of diabetic kidney disease (DKD) is essential for preventing its onset and progression. The fibrinogen-to-albumin ratio (FAR) has emerged as a novel inflammatory biomarker in various diseases, but its association with DKD in T2DM patients remains unclear. This study aimed to investigate the relationship between FAR and DKD.</p> Methods <p>Between January 2020 and September 2022, a total of 162 adult patients were retrospectively enrolled in this study. The associations between FAR levels and DKD were investigated using propensity score matching (PSM) analysis under regression analysis. Diagnostic performance of the individual or combined indicators was evaluated using receiver operating characteristic (ROC) analysis, decision curve analyses (DCA), the integrated discrimination improvement (IDI) and net reclassification improvement (NRI). Another 100 T2DM patients diagnosed by the same method were included as the validation model.</p> Results <p>RCS analysis suggested that there was a nonlinear relationship between the FAR and DKD. Univariate and multivariable logistic regression analyses showed FAR was an independent factor significantly associated with DKD before and after matching. The enhanced discriminatory ability of combining FAR and eGFR (AUC = 0.902, with 95% CI 0.853–0.950) compared to their individual performance, and the DCA and further internal and external validation confirmed their clinical relevance. NRI and IDI suggested the superior efficacy of the combined index of FAR and eGFR in this study.</p> Conclusions <p>Our results demonstrated that elevated FAR is independently associated with an increased presence of diabetic kidney disease in patients with T2DM. These findings indicate that FAR shows promise as a valuable and readily available biomarker for risk stratification and potentially for monitoring disease progression. Future prospective studies are required to validate its utility in diagnosis or treatment selection prior to any clinical application.</p>