RecruitingGlucose Metabolism in Cystic Fibrosis Related Diabetes (CFRD)The study aims to test whether use of CFTR modulators (ETI) improves fasting and post prandial glycemia by enhancing disposition index (DI) in individuals with CFRD with CFTR +ve mutation (at least one copy of F508del) on CFTR modulator (ETI) therapy (CFRDF508del+ETI). CFRD with a mutation that is not eligible for modulator therapy (CFRD-ETI) will be the control group.