A Pilot Study of a Low Glycemic Load Diet in Adults With Cystic Fibrosis

N/ACompletedNCT04519853

Boston Children's Hospital11 enrolled

Overview

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.

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.

Study Type

INTERVENTIONAL

Allocation

Purpose

TREATMENT

Masking

NONE

Enrollment

Conditions

Cystic Fibrosis Cystic Fibrosis-related Diabetes Cystic Fibrosis With Intestinal Manifestations

Interventions

Low Glycemic Load DietBEHAVIORAL

Food delivery service will provide a low glycemic load diet for 8 weeks

Eligibility

Sex: ALLMin age: 18 YearsMax age: 70 Years

Medical Language ↔ Plain English

Inclusion Criteria: 1. Diagnosis of CF 2. Diagnosis of pancreatic insufficiency, requiring pancreatic enzyme replacement 3. Oral glucose tolerance test within the past three years showing impaired glucose tolerance (2-hour glucose ≥140 mg/dL) or indeterminate glycemia (1-hour glucose ≥200), HbA1c 5.7-6.4% in the past one year, and/or or documented random glucose ≥200 in the past one year 4. BMI 21-25 kg/m2 5. 18 years and above Exclusion Criteria: 1. Current use of insulin 2. Most recent HbA1c ≥6.5% 3. History of solid organ transplant or currently listed for solid organ transplant 4. FEV1 \<50% predicted on most recent pulmonary function testing 5. Currently receiving enteral nutrition support 6. Current or anticipated pregnancy in the next 1 year 7. Hospitalization for CF exacerbation within 1 month of enrollment 8. Started or stopped treatment with Trikafta or other CFTR modulator within 3 months of enrollment 9. Currently adhering to a low glycemic index or other carbohydrate restricted diet

Locations (1)

Boston Children's Hospital

Boston, Massachusetts, United States

Outcomes

Primary Outcomes

Change in weight from baseline and 10 weeks

Anthropometric measure

Time frame: Baseline and 10 weeks

Change in percent time <54 mg/dL

Continuous glucose monitoring

Time frame: Baseline and 10 weeks

Patient reported tolerability of dietary intervention, Likert scale

Single Likert scale question of overall diet tolerability, ranging from 1 (intolerable) to 10 (completely tolerable)

Time frame: Single measurement at 10 weeks after diet completion