FEED-Cystic Fibrosis (FEED-CF)

Official title

Feeding Study to Optimize Endocrine Dysfunction in Cystic Fibrosis

Overview

The goal of this study is to determine the extent to which excess dietary sugars serve as a precipitating factor in glucose intolerance in adults with cystic fibrosis (CF), a population at especially high risk for a unique form of diabetes (CF-related diabetes, CFRD) and with standard-of-care dietary recommendations (high-calorie, high-fat) that conflict with recommendations for other forms of diabetes. This trial will investigate if the typical high-sugar, high-fat CF diet plays a role in diabetes risk and visceral fat accumulation in people with CF. A total of 30 participants will get a low-added sugar, high-fat diet and the other 30 will get a standard CF diet with no sugar restrictions. Participants will be randomized to the diet group they are assigned. All foods will be provided for 8 weeks.

Detailed description

Approximately half of adults with cystic fibrosis (CF), a genetic disease, will develop diabetes. Dietary strategies shown to be successful in preventing or treating other forms of diabetes in people without CF contradict current nutritional recommendations for people with CF. The nutrition standard-of-care in CF is prescription of an unrestricted high-calorie, high-fat diet because of malnutrition. However, the standard CF diet translates to low-quality diets, with excess added sugars well-above general population recommendations. Also the investigators have shown that people with CF have more fat around their abdominal organs (called visceral fat) compared to healthy controls. The hypothesis is that the typical high-sugar, high-fat CF diet plays a role in diabetes risk and visceral fat accumulation in people with CF. In this study, the investigators will test if a low-added sugar diet improves risk markers for diabetes and decreases visceral fat over 8 weeks. The study will recruit 60 participants with CF. A total of 30 participants will get a low-added sugar, high-fat diet and the other 30 will get a standard CF diet with no sugar restrictions. Participants will be randomized to the diet group they are assigned. All foods will be provided for 8 weeks. There will be a total of 4 study visits at the Emory Hospital clinical research unit. These will include: 1) a screening visit with an oral glucose tolerance test with blood draws to determine if they already have diabetes, 2) a baseline visit for an insulin secretion test (called glucose-potentiated arginine (GPA) stimulation test) to assess risk for diabetes, as well as magnetic resonance imaging (MRI) testing to measure visceral fat, 3) a 4-week visit for another oral glucose tolerance test and in-person check-in, and 4) an 8-week visit for another GPA and MRI. Blood samples will be collected and banked. In addition to all meals provided for 8 weeks, participants will be compensated for their time and effort. Participants will be recruited from patients seen at the Emory CF Clinic. Informed consent will be performed prior to any study testing. The investigators hope this study will contribute to the development of new standardized nutrition guidelines for people living with CF.

Interventions

• Other Low-added sugar, high-fat diet
  Consist of \<5% kcal from added sugars as recommended by the American Heart Association, and the glycemic index will be 45 or lower (25% lower than typical CF diet). The macronutrient composition of both study diets will reflect the general CF recommendations for macronutrients: 35-40% of total kcal from fat and 15-20% total kcal from protein.
• Other High-added sugar, high-fat CF diet
  Consist of ≥13% kcal from added sugars and the glycemic index will be \>60. The macronutrient composition of both study diets will reflect the general CF recommendations for macronutrients: 35-40% of total kcal from fat and 15-20% total kcal from protein.

Primary outcome measures

• Change in acute insulin response to arginine (AIRarg) from baseline [Time frame: Baseline and 8 weeks post intervention]
• Change in acute C-peptide (ACRarg) from baseline [Time frame: Baseline and 8 weeks post intervention]
• Change in visceral adipose tissue from baseline [Time frame: Baseline and 8 weeks post intervention]
• Change in fasted plasma Eh[CySS] from baseline [Time frame: Baseline and 8 weeks post intervention]

Secondary outcome measures (3)

• Change in Gastrointestinal Symptom Rating Scale (GSRS) scale [Time frame: Baseline and 8 weeks post intervention]
• Change in hepatic and pancreatic fat volume [Time frame: Baseline and 8 weeks post intervention]
• Change in fasted plasma Eh[GSSG] [Time frame: Baseline and 8 weeks post intervention]

Eligibility criteria

Inclusion criteria

• Confirmed CF diagnosis
• Ages 18 years and older
• Baseline estimated daily total added sugar intake >16 tsp, as estimated from the Dietary Screener Questionnaire (DSQ).

Exclusion criteria

• Nocturnal tube feeds
• BMI <18.5 kg/m2
• Life expectancy < 12 months
• Confirmed diagnosis of CFRD
• Screening OGTT showing fasting hyperglycemia (≥126 mg/dL)
• Chronic steroid use
• Current pregnancy or lactation
• Inability/unwillingness to consume the majority of foods on the menu during the study period
• MRI-incompatible metal that cannot be removed for testing
• Uncontrolled exocrine pancreatic insufficiency/malabsorption
• Clinically instability, defined as no changes in medical regimen (including medications and pulmonary exacerbations) for at least 21 days prior to study visit
• Initiation of CFTR modulator within previous 8 weeks OR unstable changes in weight and lung function due to CFTR modulator use
• Actively trying to gain or lose weight
• Any food allergies or intolerances that cannot be accommodated
• Any medical condition deemed by the a study physician or PI that may preclude completion of the study or interfere with primary end points.

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: No

Study design

Allocation

Randomized

Model

Parallel assignment

Masking

Triple blind

Primary purpose

Prevention

Study locations

United States · 1 center

• Emory University Hospital — Atlanta

Publications

• Zaveri S, Stecenko A, Hunt WR, Goss A, Sharma P, Hartman TJ, Easley K, Chandler JD, Burley TM, Driggers C, Ciccarella A, Zhou H, Narlow K, Ziegler TR, Daley T, Vellanki P, Alvarez J. Low-added sugar dietary intervention study to mitigate glucose intolerance and improve body composition in adults with cystic fibrosis: a protocol of a double-blind, randomised study. BMJ Open. 2024 Dec 26;14(12):e092 PMID 39725418

Identifiers

NCT: NCT05766774 · STUDY00004517 · 1R01DK133523-01 · 2025P010830

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗