Reductions in albuminuria are associated with a subsequent lower risk of kidney failure in patients with chronic kidney disease. The SGLT2 inhibitor dapagliflozin significantly reduced albuminuria in patients with type 2 diabetes and normal or near-normal kidney function. Whether this effect persists in patients with chronic kidney disease with and without type 2 diabetes is unknown. We assessed the effects of dapagliflozin on albuminuria in patients with chronic kidney disease with and without type 2 diabetes in the dapagliflozin and prevention of adverse outcomes in chronic kidney disease (DAPA-CKD) trial.DAPA-CKD was a multicentre, double-blind, placebo-controlled, randomised trial done at 386 sites in 21 countries. Patients were eligible for the trial if they had chronic kidney disease, defined as an estimated glomerular filtration rate (eGFR) between 25 mL/min per 1·73 m2 and 75 mL/min per 1·73 m2 and a urinary albumin-to-creatinine ratio (UACR) between 200 mg/g and 5000 mg/g (22·6 to 565·6 mg/mmol). Participants were randomly assigned to dapagliflozin 10 mg (AstraZeneca; Gothenburg, Sweden) once daily or matching placebo, in accordance with the sequestered, fixed randomisation schedule, using balanced blocks to ensure an approximate 1:1 ratio. Change in albuminuria was a pre-specified exploratory outcome of DAPA-CKD. Regression in UACR stage, defined as a transition from macroalbuminuria (≥300 mg/g) to microalbuminuria or normoalbuminuria (<300 mg/g), and progression in UACR stage, defined as a transition from less than 3000 mg/g to 3000 mg/g or greater, were additional discrete endpoints. The trial is registered with ClinicalTrials.gov, NCT03036150.Between Feb 2, 2017, and April 3, 2020, 4304 patients were recruited and randomly assigned to either dapagliflozin (n=2152) or placebo (n=2152). Median UACR was 949 mg/g (IQR 477 to 1885). Overall, compared with placebo, dapagliflozin reduced geometric mean UACR by 29·3% (95% CI -33·1 to -25·2; p<0·0001); relative to placebo, treatment with dapagliflozin resulted in a geometric mean percentage change of -35·1% (95% CI -39·4 to -30·6; p<0·0001) in patients with type 2 diabetes and -14·8% (-22·9 to -5·9; p=0·0016) in patients without type 2 diabetes over the follow-up visits (pinteraction<0·0001) Among 3860 patients with UACR of 300 mg/g or greater at baseline, dapagliflozin increased the likelihood of regression in UACR stage (hazard ratio 1·81, 95% CI 1·60 to 2·05). Among 3820 patients with UACR less than 3000 mg/g at baseline, dapagliflozin decreased the risk of progression in UACR stage (0·41, 0·32 to 0·52). Larger reductions in UACR at day 14 during dapagliflozin treatment were significantly associated with attenuated eGFR decline during subsequent follow-up (β per log unit UACR change -3·06, 95% CI -5·20 to -0·90; p=0·0056).In patients with chronic kidney disease with and without type 2 diabetes, dapagliflozin significantly reduced albuminuria, with a larger relative reduction in patients with type 2 diabetes. The similar effects of dapagliflozin on clinical outcomes in patients with or without type 2 diabetes, but different effects on UACR, suggest that part of the protective effect of dapagliflozin in patients with chronic kidney disease might be mediated through pathways unrelated to reduction in albuminuria.AstraZeneca.