- 1) Confirmed diagnosis of CF, defined by positive sweat test or CFTR mutation analysis according to CFF diagnostic criteria, 2) age ≥ 18y on date of consent, 3) pancreatic insufficiency, 4) recent OGTT consistent with Indeterminate-GT, IGT, CFRD w/o fasting hyperglycemia, or an established diagnosis of CFRD without fasting hyperglycemia, 5) for female subjects, negative urine pregnancy test at enrollment.