Continuous glucose monitoring is a better indicator of glucose tolerance than HbA1c in cystic fibrosis.

BACKGROUND

Systematic screening for cystic fibrosis related diabetes (CFRD) is recommended for all people living with cystic fibrosis (pwCF) from the age of 10. However, adhering to these guidelines is challenging given the cumbersome nature and potential side effects of the current test of reference, the Oral Glucose Tolerance Test (OGTT). Continuous glucose monitoring (CGM) could become an alternative to OGTT, thanks to its ease of use and to the extensive information it provides.

METHODS

We present the baseline data from a prospective observational multicentric French and Canadian cohort. Concomitant OGTT, CGM and collection of clinical data were performed in adult pwCF.

RESULTS

Complete data were available in 107 participants (73 with normal glucose tolerance, 24 with impaired glucose tolerance and 10 with cystic fibrosis related diabetes), of whom 63 % were treated with Elexacaftor/Tezacaftor/Ivacaftor. Glycated hemoglobin (HbA1c), time above 7.8mmol/L and time above 10mmol/L were lower in participants with normal glucose tolerance than in those with CFRD. Several CGM parameters associated more strongly with diagnosis of CFRD at OGTT than HbA1c (Area under the ROC curves: 0.88 for time above 10mmol/L and 0.87 for time above 7.8mmol/L, vs 0.61 for HbA1c). Spending more than 10 % of the time above 7.8mmol/L detected CFRD with 100 % sensitivity and 46% specificity.

CONCLUSIONS

Certain CGM parameters correlated more closely with diagnosis of CFRD at OGTT than HbA1c in adult pwCF, with or without treatment by Elexacaftor/Tezacaftor/Ivacaftor. If future studies confirm these results prospectively, CGM could be used as a first step to screen for CFRD.