Alternate Measures of Glucose During OGTT Testing for CFRD

Correlations Between CGM and Serum Glucose During OGTT Testing for CFRD

Although early detection and treatment of cystic fibrosis-related diabetes (CFRD) can lead to significant clinical improvements and prolong life, rates of screening are poor likely due to the burdensome nature of oral glucose tolerance testing (OGTT). The investigators propose to assess the feasibility and accuracy of two screening tools, continuous glucose monitoring (CGM) and a home OGTT kit (GTT@home). If this pilot study reveals acceptable accuracy of either device, this study will allow for future studies exploring home-based OGTT screening.

Study Overview

• Status: Recruiting
• Conditions: Cystic Fibrosis; Cystic Fibrosis-related Diabetes
• Intervention / Treatment: Diagnostic test: Oral glucose tolerance test

Detailed Description

The investigators hypothesize that there will be strong agreement between plasma glucose and glucose as measured by either CGM or GTT@home at three different timepoints during an OGTT: fasting, 1-hour, and 2-hours.

• Study Type: Observational
• Enrollment (Estimated): 30

Contacts and Locations

• Study Contact: Name: Grey Baker; Phone Number: (215)-590-3174; Email: bakerg3@chop.edu

Study Locations

• United States
  • Pennsylvania
    • Philadelphia, Pennsylvania, United States, 19104
      • Recruiting
      • Children's Hospital of Philadelphia
      • Principal Investigator: Brynn E Marks, MD, MSHPEd
      • Sub-Investigator: Melissa S Putman, MD, MSc
      • Sub-Investigator: Andrea Kelly, MD, MSCE
      • Contact: Grey Baker; Phone Number: 215-590-3174; Email: bakerg3@chop.edu

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 10 years and older (Child, Adult, Older Adult)
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

A total of 15 subjects with cystic fibrosis (CF) over 10 years of age will be approached to participate.

Description

Inclusion Criteria:

• Diagnosis of cystic fibrosis
• ≥ 10 years of age
• Fluency in written and spoken English as the GTT@Home is currently only available in English

Exclusion Criteria:

• Hospitalization or treatment with IV antibiotics or supraphysiologic glucocorticoids within 4 weeks
• Major medical or psychiatric disorders other than CF
• Use of medications known to impact the accuracy of the Dexcom G7 (hydroxyurea, >2g acetaminophen per day)
• History of severe adhesive reactions that may lead to an inability to tolerate CGM wear

Study Plan

How is the study designed?

Design Details

• Observational Models: Cohort
• Time Perspectives: Prospective

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
OGTT Cohort; All enrolled participants will complete an OGTT.	Diagnostic test: Oral glucose tolerance test; An oral glucose tolerance test will be completed. A fasting glucose will be measured. Participants will drink 1.75 g/kg of dextrose (up to a maximum of 75 grams) within 10 minutes. Glucose values will be measured at 1 hour and 2 hours.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Agreement between plasma glucose, CGM measured glucose using the Dexcom G7, and GTT@home glucose	Differences in fasting glucose will be measured by the difference in mg/dl between plasma glucose, CGM measured glucose, and GTT@home measured glucose.	Fasting glucose before OGTT
Agreement between plasma glucose, CGM measured glucose using the Dexcom G7, and GTT@home glucose	Differences in the 1 hour glucose during the OGTT will be measured by the difference in mg/dl between plasma glucose, CGM measured glucose, and GTT@home measured glucose.	1 hour mark in OGTT
Agreement between plasma glucose, CGM measured glucose using the Dexcom G7, and GTT@home glucose	Differences in the 2 hour glucose during the OGTT will be measured by the difference in mg/dl between plasma glucose, CGM measured glucose, and GTT@home measured glucose.	2 hour mark in OGTT

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Difference between plasma glucose and CGM measured glucose after the fasting glucose	Absolute differences between the glucose measurements will be measured in mg/dL	Up to 20 minutes after the fasting glucose
Difference between plasma glucose and CGM measured glucose after the 1 hour mark during the OGTT.	Absolute differences between the glucose measurements will be measured in mg/dL	Up to 20 minutes after the 1 hour mark in the OGTT
Difference between plasma glucose and CGM measured glucose after the 2 hour mark during the OGTT.	Absolute differences between the glucose measurements will be measured in mg/dL	Up to 20 minutes after the 2 hour mark in the OGTT
The ability of untrained participants to successfully complete the GTT@home kit without any guidance from the research team	Number of steps successfully completed as measured by the GTT@home instruction manual.	Up to 2 hours
Impact of wearing a real-time CGM on participants' awareness of the importance of screening for and diagnosing CFRD.	60 minute semi-structured interviews will be conducted with participants. Transcripts will be analyzed using semantic content analysis	Within 2 weeks after removal of the CGM
Perceived benefits and burdens of CGM use	Participants will complete a CGM Benefits and Burdens survey, a 16-item measure used to assess perceptions of CGM technology in people with type 1 diabetes. Surveys may be completed on paper or online, as per the participant's preference. The survey is scored on a 5-point scale (agree/disagree scale).	Within 2 weeks after removal of the CGM
Agreement between the categorical diagnosis of normal glucose tolerance (NGT), impaired glucose tolerance (IGT), indeterminate glycemia (INDET), and CFRD as defined by plasma glucose, CGM glucose, and GTT@home glucose.	Categorical diagnosis of glucose tolerance as measured by plasma glucose, CGM measured glucose using the Dexcom G7, and GTT@home glucose.	Up to 2 hours

Collaborators and Investigators

• Sponsor: Children's Hospital of Philadelphia
• Collaborators: Cystic Fibrosis Foundation

Study record dates

Study Major Dates

• Study Start (Actual): July 17, 2023
• Primary Completion (Estimated): February 1, 2025
• Study Completion (Estimated): February 1, 2026

Study Registration Dates

• First Submitted: October 3, 2022
• First Submitted That Met QC Criteria: October 3, 2022
• First Posted (Actual): October 5, 2022

Study Record Updates

• Last Update Posted (Actual): March 6, 2024
• Last Update Submitted That Met QC Criteria: March 5, 2024
• Last Verified: March 1, 2024

More Information

Terms related to this study

• Keywords: continuous glucose monitor; oral glucose tolerance test
• Additional Relevant MeSH Terms: Digestive System Diseases; Pathologic Processes; Respiratory Tract Diseases; Lung Diseases; Infant, Newborn, Diseases; Genetic Diseases, Inborn; Pancreatic Diseases; Fibrosis; Cystic Fibrosis
• Other Study ID Numbers: 22-020249

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: Yes