Twelve-Month Albuminuria Response to Finerenone in Patients With Chronic Kidney Disease and Type 2 Diabetes Mellitus: A Real-World Study

IntroductionFinerenone, a selective non-steroidal mineralocorticoid receptor antagonist, reduces albuminuria and cardiorenal risk in patients with chronic kidney disease (CKD) and type 2 diabetes mellitus (T2DM).However, real-world data on its longer-term effects across different levels of baseline albuminuria remain limited.This study evaluated longitudinal changes in urinary albumin concentration, renal function, and serum potassium during 12 months of finerenone treatment in routine nephrology practice. Materials and methodsThis retrospective, observational, single-center study included 68 patients with CKD and T2DM receiving finerenone in addition to optimized renin-angiotensin system blockade.Patients receiving sodium-glucose cotransporter-2 inhibitors, glucagon-like peptide-1 receptor agonists, other mineralocorticoid receptor antagonists, or calcium dobesilate were excluded.Urinary albumin concentration was measured in spot urine samples and expressed in mg/L.Patients were stratified according to baseline albuminuria into Group 1 (30-300 mg/L; n=28), Group 2 (>300 to ≤1000 mg/L; n=33), and Group 3 (>1000 mg/L; n=7).Urinary albumin concentration, estimated glomerular filtration rate (eGFR), serum albumin, and serum potassium were evaluated at baseline and at three, six, and 12 months. ResultsMean urinary albumin concentration decreased progressively from 383.4±328.7 mg/L at baseline to 230.0±240.1 mg/L at three months, 115.6±120.1 mg/L at six months, and 48.5±50.1 mg/L at 12 months (p<0.001),corresponding to a mean 12-month relative reduction of 86.8±6.1%.The relative reduction did not differ significantly among baseline albuminuria groups (85.2%, 88.4%, and 85.8%, respectively; p=0.258).Mean eGFR remained stable at three months and was higher than baseline at six and 12 months, reaching 65.3±17.7 mL/min/1.73m 2 at month 12 (adjusted p<0.001).Serum potassium increased significantly during follow-up (p<0.001).Sixteen patients (23.5%) developed at least one potassium concentration >5.5 mmol/L; all such episodes occurred among patients receiving finerenone 20 mg/day and were managed by temporary treatment interruption for two weeks, followed by reinitiation at 10 mg/day after normalization of serum potassium. DiscussionThe observed albuminuria reduction was substantially greater than that reported in randomized finerenone trials.However, urinary albumin concentration in spot urine samples is influenced by urine dilution and is not directly comparable with urinary albumin-to-creatinine ratio measurements.The absence of a control group also limits causal interpretation of the observed albuminuria and eGFR changes. ConclusionsIn this real-world cohort of patients with CKD and T2DM, finerenone treatment was associated with a progressive reduction in urinary albumin concentration over 12 months, with comparable proportional reductions across baseline albuminuria groups.Serum potassium elevations required temporary treatment interruption followed by dose reduction in a subset of patients.Larger prospective controlled studies using standardized albuminuria measurements are needed to confirm these findings.