A Pilot Study of a Low Glycemic Load Diet in Adults With Cystic Fibrosis
Condition: Cystic Fibrosis; Cystic Fibrosis-related Diabetes; Cystic Fibrosis With Intestinal Manifestations
MeSH terms: Cystic Fibrosis; Fibrosis
Study type: Interventional

Summary: 
      This pilot study will evaluate the safety and tolerability of a low glycemic load dietary
      intervention in adult patients with cystic fibrosis (CF) in a rigorous feeding study.
      Specific emphasis will be placed on changes in weight, body composition, and glycemic
      measures obtained via continuous glucose monitor (CGM) usage.
    

Detailed description: 
      Non-pulmonary complications of cystic fibrosis (CF) are becoming increasingly prevalent with
      the changing landscape of CF care. CF related diabetes mellitus (CFRD) and CF related
      gastrointestinal (GI) complications have significant effects on morbidity and mortality.
      Treatment options are limited to insulin therapy for CFRD and symptom control for most GI
      complications.

      BMI is a well-established marker of morbidity and mortality in patients with CF. Many
      patients consume a high carbohydrate intake to meet their increase caloric needs, potentially
      leading to complications including post-prandial hyperglycemia, increased inflammation, and
      abnormal GI motility. Dietary recommendations for children and adults with CF are limited and
      based entirely on consensus and expert opinion. As patients with CF live longer with highly
      effective modulator therapy, it is important to understand the effects of dietary composition
      on short and long-term endocrine, GI, and pulmonary outcomes.

      The investigators will conduct a prospective, open-label pilot study in adults with CF and
      impaired glucose tolerance or indeterminate glycemia to establish the safety and tolerability
      of a low glycemic load (LGL) diet. Subjects will initially follow their standard diet for a
      2-week run-in period, then transition to a LGL diet provided by a food delivery service for
      the remaining 8 weeks. The investigators will also investigate potential short-term outcomes
      of dietary carbohydrate manipulation, including glycemic variability measured by continuous
      glucose monitor (CGM), body composition via DXA, GI symptoms, and quality of life measures.

      The investigators hypothesize that a diet lower in carbohydrate content will be safe,
      tolerable, and associated with weight maintenance or gain, and that a LGL diet will result in
      decreased glycemic variability via CGM, improved GI symptoms, increased lean to fat mass
      ratio, and improved quality of life measures over an 8-week period.
    

Intervention name(s): Low Glycemic Load Diet
Intervention type(s): Behavioral
Intervention description(s): Food delivery service will provide a low glycemic load diet for 8 weeks
Intervention model: Single Group Assignment
Intervention model description: Single dietary treatment arm with run-in period as a control
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: Cystic Fibrosis Related Diabetes; Low Glycemic Load; Continuous Glucose Monitoring