# High vs Low Glycemic Index Mixed Meal Tolerance Test in Children and Adolescents with Cystic Fibrosis

> **NIH NIH R21** · EMORY UNIVERSITY · 2023 · $195,625

## Abstract

PROJECT SUMMARY
Cystic fibrosis related diabetes (CFRD) is one of the most common co-morbidities seen in
patients with cystic fibrosis. Unlike CF patients without diabetes, CFRD patients have a higher
mortality rates and a decline in pulmonary function due to abnormalities in glucose tolerance
that often predate the diagnosis of CFRD. Sustained exposure of the islet cell to modestly
elevated blood glucose levels is often cited as an important cause of beta cell dysfunction.
Recent published data from our adult CF center and others show that patients with CF often
consume a low-quality diet with high added sugar intake. We are particularly concerned that a
diet which is abundant in high glycemic index (GI) foods and sugar sweetened beverages (SSB)
may increase beta cell dysfunction in CF. We propose that we can successfully conduct a
feasibility study, which will involve the consenting and randomizing of participants, the following
of protocols and gathering of study data, and an evaluation of procedural acceptability from
participants. Secondarily, we anticipate that an analysis of outcome data collected from this
feasibility study will allow for preliminary data of the association between postprandial changes
in glucose and redox imbalance following a mixed meal tolerance test. To test this, we propose
the following Aims: Aim 1) Determine the feasibility and acceptability of conducting a
randomized, balanced 2x2 factorial design that evaluates postprandial changes in glucose
following exposure to a mixed meal that varies by GI and consumption of a SSB. A few of the
metrics to evaluate feasibility will include a willingness from participants to consent and be
randomized (<20% refusal), high protocol fidelity among investigators and participants (≥85%),
high visit attendance by participants (≥85%) and high retention (≥80%), and completion of the
primary clinical outcome measurements (≥90%), among others. Aim 2) Evaluate preliminary
changes in postprandial hyperglycemia, islet cell function and incretin response to a high or low
GI mixed meal tolerance test (MMTT) with and without SSBs in adolescents with CF. Subjects
will be equally randomized to either sugar sweetened beverage plus high glycemic index
(SSB+HI-GI), sugar sweetened beverage plus low glycemic index (SSB+LO-GI), no sugar
sweetened beverage plus high glycemic index (NSSB+HI-GI), or no sugar sweetened beverage
plus low glycemic index (NSSB+LO-GI) using permuted blocks. Sub Aim 2) Determine if an
association exists between high vs. low GI MMTT with and without SSB and changes in plasma
aminothiol redox imbalance.

## Key facts

- **NIH application ID:** 10700968
- **Project number:** 5R21DK128731-02
- **Recipient organization:** EMORY UNIVERSITY
- **Principal Investigator:** Tanicia Daley
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2023
- **Award amount:** $195,625
- **Award type:** 5
- **Project period:** 2022-09-15 → 2025-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10700968

## Citation

> US National Institutes of Health, RePORTER application 10700968, High vs Low Glycemic Index Mixed Meal Tolerance Test in Children and Adolescents with Cystic Fibrosis (5R21DK128731-02). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10700968. Licensed CC0.

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