Alternate Measures of Glucose During OGTT Testing for CFRD

Completed

• Conditions: Cystic Fibrosis-related Diabetes; Cystic Fibrosis
• Interventions: Diagnostic Test: Oral glucose tolerance test

• Registration Number: NCT05568134
• Lead Sponsor: Children's Hospital of Philadelphia

Brief Summary

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.

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 Timeline

• Study First Submitted: 2022-10-03
• Study First Submitted QC: 2022-10-03
• Study First Posted: 2022-10-05
• Study Start: 2023-07-17
• Primary Completion: 2024-12-13
• Study Completion: 2024-12-13
• Status Verified: 2025-02
• Last Update Submitted: 2025-02-21
• Last Update Posted: 2025-02-24

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 14

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 & Design

• Study Type: OBSERVATIONAL
• Study Design: Not specified

Arm && Interventions

Group	Intervention	Description
OGTT Cohort	Oral glucose tolerance test	All enrolled participants will complete an OGTT.

Primary Outcome Measures

Name	Time	Method
Agreement between plasma glucose, CGM measured glucose using the Dexcom G7, and GTT@home glucose	2 hour mark in OGTT	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.

Secondary Outcome Measures

Name	Time	Method
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.	Up to 2 hours	Categorical diagnosis of glucose tolerance as measured by plasma glucose, CGM measured glucose using the Dexcom G7, and GTT@home glucose.
Difference between plasma glucose and CGM measured glucose after the fasting glucose	Up to 20 minutes after the fasting glucose	Absolute differences between the glucose measurements will be measured in mg/dL
Difference between plasma glucose and CGM measured glucose after the 2 hour mark during the OGTT.	Up to 20 minutes after the 2 hour mark in the OGTT	Absolute differences between the glucose measurements will be measured in mg/dL
Impact of wearing a real-time CGM on participants' awareness of the importance of screening for and diagnosing CFRD.	Within 2 weeks after removal of the CGM	60 minute semi-structured interviews will be conducted with participants. Transcripts will be analyzed using semantic content analysis
The ability of untrained participants to successfully complete the GTT@home kit without any guidance from the research team	Up to 2 hours	Number of steps successfully completed as measured by the GTT@home instruction manual.
Perceived benefits and burdens of CGM use	Within 2 weeks after removal of the CGM	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).
Difference between plasma glucose and CGM measured glucose after the 1 hour mark during the OGTT.	Up to 20 minutes after the 1 hour mark in the OGTT	Absolute differences between the glucose measurements will be measured in mg/dL

Trial Locations

Locations (1)

Children's Hospital of Philadelphia; 🇺🇸 Philadelphia, Pennsylvania, United States