Advanced glycation end-products (AGEs) play a critical role in diabetic kidney disease (DKD) through oxidative stress, endothelial dysfunction, and extracellular matrix remodeling. Skin autofluorescence (SAF) provides a noninvasive estimate of AGE accumulation. However, its role in identifying diabetic kidney disease (DKD) remains uncertain. This study aimed to investigate the relationship between SAF and renal function, and to assess the predictive value of SAF for reduced estimated glomerular filtration rate (eGFR < 60 mL/min/1.73 m²) in patients with T2DM.

A cross-sectional study including 148 adults with T2DM was conducted. SAF was measured using the mu AGE Reader device. Clinical and laboratory data, including age, sex, body mass index (BMI), waist circumference, fasting glucose, HbA1c, lipid profile, and creatinine, were collected. Correlation analysis, logistic regression, and ROC curve evaluation were performed to assess the relationship between SAF and renal impairment. Optimal cut-off determination used Liu’s method.

96 participants (64.9%) had reduced eGFR. SAF levels were significantly higher among those with reduced eGFR (2.9 ± 0.7 vs. 2.6 ± 0.6 AU, p <0.05). SAF correlated inversely with eGFR (r = –0.31, p <0.05), with a magnitude comparable to correlations for age (r = –0.34) and ACR (r = –0.36). In multivariable linear regression, SAF remained an independent determinant of eGFR (β = –7.67, p < 0.05) alongside age and ACR, collectively explaining 22.9% of variance in renal function. In logistic regression, SAF was significantly associated with reduced eGFR in unadjusted analysis (OR 2.21, 95% CI 1.24–3.94; p = 0.007), but its predictive strength declined after adjustment for clinical covariates, with age emerging as the predominant predictor. Incorporating SAF into a clinical model (age, BMI, sex) showed a limited incremental improvement (pseudo-R² from 0.097 to 0.117, AUC from 0.70 to 0.71). The optimal SAF cut-off was 2.65 AU (sensitivity 0.67, specificity 0.60, AUC=0.63).

SAF is independently associated with renal dysfunction in T2DM but shows modest discriminative ability and limited added value beyond traditional predictors.