Longitudinal Trajectories of Albuminuria and eGFR in Type 2 Diabetes Mellitus: Natural Progression of Diabetic Kidney Disease.

Background: This longitudinal cohort study is aimed at examining the natural progression trajectories of diabetic kidney disease (DKD) in Type 2 diabetes mellitus (T2DM), assessing estimated glomerular filtration rate (eGFR) and albuminuria patterns over time. Methods: This longitudinal observational study analyzed 694 hospitalized patients with T2DM, featuring a cohort with a median age of 59.0 years (interquartile range [IQR] 52.2-67.0) and a median diabetes duration of 12.0 years (IQR 6.0-18.0). The baseline population included 258 female participants (37.2%), with longitudinal data collected over a 4.5-year follow-up period conducted between March 2013 and January 2025. DKD was diagnosed per the 2024 ADA Standards of Medical Care in Diabetes. Disease severity stratification employed two validated biomarkers: urinary albumin excretion rate (AER) and eGFR calculated using the Chronic Kidney Disease Epidemiology Collaboration equation. Results: The analytical cohort comprised 421 participants in the urinary AER group and 487 in the eGFR group. Baseline albuminuria stratification revealed 61.3% normoalbuminuria, 36.6% microalbuminuria, and 2.4% macroalbuminuria. Over 4.5 years of follow-up, 9.9% demonstrated albuminuria stage progression. The prevalence of G1, G2, G3, and G4 was 51.4%, 37.7%, 10.5%, and 0.5%, respectively, with 32.5% exhibiting renal function deterioration. Albuminuria progression correlated with smoking, alcohol consumption, elevated baseline thyroid-stimulating hormone (TSH), and increasing waist circumference, while eGFR decline associated with male sex, advanced age, prolonged diabetes duration, and elevated baseline urinary AER. Conclusion: Longitudinal analysis of T2DM patients revealed an escalation in the prevalence of micro- or macroalbuminuria and renal dysfunction. Disease progression predominated over regression across the cohort. Key modifiable risk factors associated with DKD progression included tobacco use, alcohol intake, elevated baseline TSH, increasing waist circumference, male sex, age, prolonged diabetes duration, and elevated baseline urinary AER.