Based on Bellin et al. small pilot study, demonstrated that in a 14-year-old male patient with newly diagnosed CFRD, who had not received insulin treatment during the study or beforehand, daily oral ivacaftor therapy over 4 weeks did not enhance the acute, rapid-phase insulin response, measured by intravenous glucose tolerance test (IVGTT). This evidence concerns the gene INS and cystic fibrosis-related diabetes.