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NCT Number: NCT05568134

Alternate Measures of 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.

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Key information

Conditions

Cystic Fibrosis Congenital, Hereditary, and Neonatal Diseases and Abnormalities Cystic Fibrosis-related Diabetes Digestive System Diseases Genetic Diseases, Inborn Infant, Newborn, Diseases Lung Diseases Pancreatic Diseases Respiratory Tract Diseases

Age range

10 year and older

Sex eligibility

All sexes

Study type

Observational

Primary location

Children's Hospital of Philadelphia

Philadelphia, Pennsylvania, 19104, United States

About this study

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.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

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

Treatment and study plan

Oral glucose tolerance test

Diagnostic 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.

Primary outcomes

  1. Agreement between plasma glucose, CGM measured glucose using the Dexcom G7, and GTT@home glucose

    Time frame: Fasting glucose before OGTT

    Differences in fasting glucose will be measured by the difference in mg/dl between plasma glucose, CGM measured glucose, and GTT@home measured glucose.

  2. Agreement between plasma glucose, CGM measured glucose using the Dexcom G7, and GTT@home glucose

    Time frame: 1 hour mark in OGTT

    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.

  3. Agreement between plasma glucose, CGM measured glucose using the Dexcom G7, and GTT@home glucose

    Time frame: 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 outcomes

  1. 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.

    Time frame: 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.

  2. Difference between plasma glucose and CGM measured glucose after the fasting glucose

    Time frame: Up to 20 minutes after the fasting glucose

    Absolute differences between the glucose measurements will be measured in mg/dL

  3. Difference between plasma glucose and CGM measured glucose after the 1 hour mark during the OGTT.

    Time frame: Up to 20 minutes after the 1 hour mark in the OGTT

    Absolute differences between the glucose measurements will be measured in mg/dL

  4. Difference between plasma glucose and CGM measured glucose after the 2 hour mark during the OGTT.

    Time frame: Up to 20 minutes after the 2 hour mark in the OGTT

    Absolute differences between the glucose measurements will be measured in mg/dL

  5. The ability of untrained participants to successfully complete the GTT@home kit without any guidance from the research team

    Time frame: Up to 2 hours

    Number of steps successfully completed as measured by the GTT@home instruction manual.

  6. Impact of wearing a real-time CGM on participants' awareness of the importance of screening for and diagnosing CFRD.

    Time frame: 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

  7. Perceived benefits and burdens of CGM use

    Time frame: 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).

Sponsors and collaborators

Lead sponsor

Children's Hospital of Philadelphia

Other

Collaborators

  • Cystic Fibrosis Foundation

Registry information

Official study title

Correlations Between CGM and Serum Glucose During OGTT Testing for CFRD

Important dates

Study start
2023
Primary completion
2024
Study completion
2024
First posted
Oct 5, 2022
Registry last updated
Feb 24, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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