In the last decades, many large randomized controlled trials have been conducted to assess the efficacy and safety of new interventions for the treatment of diabetic kidney disease (DKD). Unfortunately, these trials failed to demonstrate additional kidney or cardiovascular protection. One of the explanations for the failure of these trials appears to be the large variation in drug response between individual patients. All trials to date tested a drug which was targeted to a large heterogeneous population assuming that every individual will show a similar beneficial respond to the drug. Post hoc analyses from the past clinical trials, however, suggest that individual patients show a marked variation in drug response. This highlights the need...