Comparison of Renal Function Decline in Proteinuric and Non-Proteinuric Diabetic Kidney Disease: A Retrospective Single-Centre Study

Background Diabetic kidney disease (DKD) has traditionally been characterized by albuminuria; however, a substantial proportion of patients develop reduced kidney function without significant proteinuria. Materials and Methods This retrospective single-center study included patients with DKD attending a tertiary nephrology clinic in Sri Lanka between August 2017 and August 2019. Patients were categorized into proteinuric DKD (P-DKD) and non-proteinuric DKD (NP-DKD) groups based on baseline proteinuria status. Renal function decline was assessed as a change in estimated glomerular filtration rate (eGFR) over follow-up. Multivariable regression analysis adjusted for age, sex, baseline eGFR, diabetes duration, blood pressure, RAAS inhibitor use, and diabetic retinopathy. Results A total of 302 patients were included (mean age 66 ± 9.6 years; 69.5% male). Patients with P-DKD demonstrated greater decline in eGFR over 24 months compared with NP-DKD (30→24 vs 38→30 mL/min/1.73 m 2 ), and this association remained significant after adjustment. Patients with NP-DKD were older, had better baseline renal function, fewer microvascular complications, and more favorable cardiovascular profiles at baseline. RAAS inhibitor use was more frequent in P-DKD and was associated with slower eGFR decline, although causal inference is limited. Conclusion P-DKD and NP-DKD represent distinct clinical phenotypes. Proteinuria remains a key predictor of renal progression, while NP-DKD demonstrates a slower decline but occurs in an older population.