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

This study will evalute the effect of a low glycemic load (LGL diet on dysglycemia, insulin requirements, DXA-derived body composition, gastrointestinal symptoms and quality of life measures in adults with cystic fibrosis-related diabetes (CFRD). We will use continuous glucose monitors (CGM) to assess the LGL diet both in a controlled setting (via a meal delivery company) and in free-living conditions.

Inclusion Criteria:18 years and aboveGenetically confirmed diagnosis of CFDiagnosis of pancreatic insufficiency, requiring pancreatic enzyme replacementCriteria 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 insulinExclusion Criteria:FEV1 <50% predicted on most recent pulmonary function testingBMI <18 kg/m2Currently receiving enteral nutrition support via GT feedsPregnancy, plan to become pregnant in the next 3-months, or sexually active without use of contraceptionUse of IV antibiotics or systemic supraphysiologic glucocorticoids for CF exacerbation within 1 monthStarted or stopped treatment with a CFTR modulator within 3 months of enrollmentCurrently adhering to an LGL or other carbohydrate-restricted diet (carbohydrate intake <30% of total daily caloric intake)