In the Functional Lesion Assessment of Intermediate Stenosis to Guide Revascularization (DEFINE-FLAIR) trial, researchers compared 1-year clinical results of instantaneous wave-free ratio (iFR)-guided or fractional flow reserve (FFR)-guided treatment in individuals with and without diabetes. Two thousand four hundred ninety-two patients (mean age was 66 years) were randomly assigned in a 1:1 ratio to undergo either iFR-guided or FFR-guided coronary revascularization. Between January 2014 and December 2015, data were analyzed. No significant difference was found in major adverse cardiac event rates between iFR-guided and FFR-guided groups in both populations with and without diabetes without significant interaction at 1 year. Even with the iFR-guided or FFR-guided treatment, the diabetes population exhibited a significantly higher risk of MACE than the nondiabetes population. The iFR-guided and FFR-guided therapy demonstrated a similar danger of MACE and offered equal safety in choosing the target for revascularization among diabetes patients.