Continuous Glucose Monitoring as an alternative for Cystic Fibrosis Related diabetes screening and diagnosis.

BACKGROUND AND AIMS: The data regarding the capacity of HbA1c and Continuous Glucose Monitoring (CGM) to diagnose Cystic Fibrosis Related Diabetes (CFRD) are uncertain. We studied HbA1c, classical CGM indexes, and novel glucodensities CGM metrics' ability to distinguish CFRD based on Oral Glucose Tolerance Test (OGTT) results.

METHODS

We carried out a prospective observational study involving 38 patients who had had an OGTT test within the previous 6 months and who accepted wearing a CGM sensor for 14 days. Patients answered a questionnaire regarding preferences for CFRD screening.

RESULTS

Participants reported a preference for a simpler method for CFRD screening, such as HbA1c, but CGM was better accepted than OGTT. Regarding CGM metrics, time above 180 mg/dL over 6 % presented a sensitivity of 93 % (p = 0.042) and time above 140 mg/dL over 20 %, a specificity of 90 % (p = 0.032) for CFRD diagnosis. CGM metrics distinguished CFRD better than HbA1c, but glucodensities improved CGM diagnostic capacity with sensitivity and specificity over 85 %.

CONCLUSION

In this exploratory study, glucodensities show better discriminatory capacity than HbA1c and CGM classic metrics in distinguishing early mild CFRD. This study supports the need for future larger prospective studies to define the most accepted screening method for CFRD, as well as the optimal cut-off point of CGM metrics and/or glucodensities for the diagnosis of CFRD.