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.

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.

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