<jats:title>Abstract</jats:title><jats:sec><jats:title>Aims/Introduction</jats:title><jats:p>We evaluated the effect of co‐administration of esaxerenone and a sodium–glucose cotransporter 2 (SGLT2) inhibitor on the magnitude of serum potassium elevation in Japanese patients with diabetic kidney disease.</jats:p></jats:sec><jats:sec><jats:title>Materials and Methods</jats:title><jats:p>We carried out a prespecified subanalysis of data from two phase III studies: a multicenter, randomized, double‐blind, placebo‐controlled trial in patients with type 2 diabetes and microalbuminuria (J308); and a multicenter, single‐arm, open‐label trial in patients with type 2 diabetes and macroalbuminuria (J309). Changes in serum potassium levels during the studies and other measures were evaluated according to SGLT2 inhibitor use.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>In both studies, time‐course changes in serum potassium levels, and incidence rates of serum potassium elevation were lower in patients with co‐administration of SGLT2 inhibitor in both the placebo and esaxerenone groups than those without the inhibitor. In contrast, time‐course changes and mean percentage changes from baseline in urinary albumin‐to‐creatinine ratio, the proportion of patients with albuminuria remission and time‐course changes in blood pressure did not change with or without SGLT2 inhibitor, whereas the albumin‐to‐creatinine ratio and blood pressure were reduced with esaxerenone. The blood glucose‐lowering effect of SGLT2 inhibitor was not affected by esaxerenone.</jats:p></jats:sec><jats:sec><jats:title>Conclusions</jats:title><jats:p>In Japanese patients with type 2 diabetes and albuminuria treated with esaxerenone, concomitant use of SGLT2 inhibitor reduced the magnitude of serum potassium elevation without any change of its antihypertensive and albuminuria‐suppressing effects. Co‐administration of esaxerenone and SGLT2 inhibitor might be a beneficial treatment option for patients with diabetic kidney disease.</jats:p></jats:sec>