From a retrospective audit of the cardiac catheter lab database and a review of the literature we have estimated that a sample size of approximately 250 patients with DM and CKD (eGFR < 60 ml/ml) will be needed. We envisage that that we will encounter at least 50 cases of CIN from this cohort. (based on an expected incidence of CIN between 15−30% in this group). Looking for a study rate difference of at least 25%, for power of 95% and confidence intervals of 95% (with Fleiss correction) we will need at least 204 evaluable patients (to avoid Type 2 error). In view of potential drop−out of 10−15% we therefore intend to recruit 250 patients By using C statistics (Receiver operator curve analysis) we will be able to confirm or otherwise that either a particular biomarker or a combination of several biomarkers within 18 hours of procedure will increase the predictive power of CIN developing 72 hours later.