Aim: To evaluate the effect of finerenone by baseline HbA1c, HbA1c variability, diabetes duration and baseline insulin use on cardiorenal outcomes and diabetes progression. Materials and Methods: Composite efficacy outcomes included cardiovascular (cardiovascular death, non-fatal myocardial infarction, non-fatal stroke or hospitalization for heart failure), kidney (kidney failure, sustained ≥ 57% estimated glomerular filtration rate decline or renal death) and diabetes progression (new insulin initiation, increase in antidiabetic medication, 1.0% increase in HbA1c from baseline, new diabetic ketoacidosis diagnosis or uncontrolled diabetes). Results: In 13 026 participants, risk reductions in the cardiovascular and kidney composite outcomes with finerenone versus placebo were consistent across HbA1c quartiles (P interaction.52 and.09, respectively), HbA1c variability (P interaction.48 and.10), diabetes duration (P interaction.12 and.75) and insulin use (P interaction.16 and.52). HbA1c variability in the first year of treatment was associated with a higher risk of cardiovascular and kidney events (hazard ratio [HR] 1.20; 95% confidence interval [CI] 1.07-1.35; P =.0016 and HR 1.36; 95% CI 1.21-1.52; P <.0001, respectively). There was no effect on diabetes progression with finerenone or placebo (HR 1.00; 95% CI 0.95-1.04). Finerenone was well-tolerated across subgroups; discontinuation and hospitalization because of hyperkalaemia were low. Conclusions: Finerenone efficacy was not modified by baseline HbA1c, HbA1c variability, diabetes duration or baseline insulin use. Greater HbA1c variability appeared to be associated with an increased risk of cardiorenal outcomes.