Associations of remnant cholesterol and apolipoprotein B with kidney function decline and progression to kidney failure in hospitalized patients with type 2 diabetic kidney disease: a retrospective cohort study

Diabetic kidney disease (DKD) is one of the leading causes of kidney failure (KF). Emerging lipid markers such as remnant cholesterol (RC) and apolipoprotein B (ApoB) have been associated with kidney disease progression. However, no study has comprehensively evaluated the associations of these two markers—analyzed both continuously and jointly—with kidney function decline and progression to KF among patients with established DKD. In this retrospective cohort study, we included 472 hospitalized patients with DKD. RC and ApoB were primarily analyzed as continuous variables, with effects expressed per 1‑standard deviation (SD) increment. For descriptive purposes, patients were also categorized into four joint groups according to baseline medians (RC: 0.76 mmol/L; ApoB: 0.91 g/L). Mixed‑effect regression models were used to estimate the eGFR slope, and Cox proportional hazards models were used to assess KF risk. During a median follow‑up of 26.4 months (among 435 patients after excluding those with follow‑up < 6 months), 59 patients (13.6%) developed KF. In continuous‑variable analyses, each 1‑SD increase in RC was associated with a faster eGFR decline (slope: −1.52 mL/min/1.73 m²/year; 95% CI: −2.55 to − 0.49; P = 0.004) and a higher KF risk (HR = 1.40; 95% CI: 1.11 to 1.77; P = 0.004); each 1‑SD increase in ApoB was associated with a faster decline (slope: −2.21 mL/min/1.73 m²/year; 95% CI: −3.26 to − 1.16; P < 0.001) and a higher KF risk (HR = 1.33; 95% CI: 1.06 to 1.68; P = 0.015). In the joint categorization analysis, patients with above‑median levels of both markers showed the largest effect estimates for both eGFR decline (β = −5.30; 95% CI: −7.61 to − 3.00) and KF risk (HR = 3.19; 95% CI: 1.46 to 7.00). In this single‑center cohort of hospitalized patients with DKD, higher levels of RC and ApoB were significantly associated with faster kidney function decline and increased KF risk. Monitoring these biomarkers may aid in risk stratification and inform targeted management, though prospective validation is warranted.