The Effects of a Low Glycemic Load Diet on Dysglycemia and Body Composition in Adults With Cystic Fibrosis-Related Diabetes

Inclusion Criteria: * 18 years and above * Genetically confirmed diagnosis of CF * Diagnosis of pancreatic insufficiency, requiring pancreatic enzyme replacement * Criteria for CFRD: A.) Most recent OGTT 2-hour glucose \>200 mg/dL within the past two years, and/or; B.) HbA1c \>6.5% in the past two years, and/or; C.) Current use of insulin Exclusion Criteria: * FEV1 \<50% predicted on most recent pulmonary function testing * BMI \<18 kg/m2 * Currently receiving enteral nutrition support via GT feeds * Pregnancy, plan to become pregnant in the next 3-months, or sexually active without use of contraception * Use of IV antibiotics or systemic supraphysiologic glucocorticoids for CF exacerbation within 1 month * Started or stopped treatment with a CFTR modulator within 3 months of enrollment * Currently adhering to an LGL or other carbohydrate-restricted diet (carbohydrate intake \<30% of total daily caloric intake)