Inclusion Criteria:  Able and willing to provide written informed consent Adults ≥ 18years old Type 2 Diabetes CKD defined as eGFR 25-60ml/min Albuminuria with uACR measured at >33.9.mg/mmol (300mg/g) On a stable (>4 weeks) of sub-maximal RASi dose, defined as any ACE or ARB dose up to and including 50% of maximum dose with evidence of hyperkalaemia potassium level >5.0mmol/l OR not currently on RASi therapy due to documented issues of hyperkalaemia in the past necessitating RASi discontinuation  Exclusion Criteria:  Active malignancy Patients who lack capacity to give informed consent GI disturbance/chronic diarrhoea/stoma Subjects with a life expectancy of less than 3 months. Women who are pregnant, lactating, planning to become pregnant or unwilling to use effective methods of contraception during the study. Presence of any condition which, in the opinion of the investigator, places the subject at undue risk or potentially jeopardizes the quality of the data to be generated including NYHA class III/IV. History of acute eGFR fall with RASi therapy (>30% in eGFR on initiation of RASi therapy) Known hypersensitivity or previous anaphylaxis to SZC or Irbesartan Hypotension: BP <120/70mm/hg at screening despite no antihypertensive agent use Uncontrolled Blood pressure: BP >170/110 at screening Evidence of prolonged QT on ECG QTc(f)>550msec History of QT prolongation associated with other medications that required discontinuation of that medication Treatment with lithium, or dual blockade with ACEi and ARB or mineralocorticoid inhibitor History of congenital long QT syndrome Symptomatic or uncontrolled atrial fibrillation despite treatment, or asymptomatic sustained ventricular tachycardia. Subjects with atrial fibrillation controlled by medication are permitted Current or recent (within 3 months) participation in a clinical trial involving an investigational medicinal product. Current treatment with a potassium binder medication