Impact of elexacaftor/tezacaftor/ivacaftor on glucose tolerance in adolescents with cystic fibrosis

Abstract

Background: Highly effective CFTR modulators, such as elexacaftor/tezacaftor/ivacaftor (ETI), herald a new era in therapeutic strategy of cystic fibrosis (CF). ETI impact on glucose tolerance remains controversial.

Methods: All the participants underwent a baseline oral glucose tolerance test (OGTT) before ETI initiation (M0) and 12 months (M12), and at 24 months if possible. The cohort was stratified in two subgroups based on the baseline OGTT: normal glucose tolerance (NGT) and abnormal glucose tolerance (AGT) defined by impaired fasting glucose or impaired glucose tolerance or diabetes not requiring insulin treatment.

Results: We included 106 adolescents with CF (age 14.1±1.5 years), 75 with NGT, 31 with AGT. The baseline characteristics of the two groups were similar except for a higher glucose level at 1 and 2-h OGTT in the AGT group. ETI induced an increase in BMIz-score and in Forced Expiratory Volume in 1 second (FEV1) (p<0.001). After 12 months, participants with NGT did not experience any change of 1-h and 2-h glucose. By contrast, those with AGT displayed a reduction of 2-h glucose at M12 (p=0.006). 15out of the 31 (48%) adolescents in the AGT group reversed to NGT but 9/75 (17%) in the NGT group progressed to AGT. 3 participants with CF related diabetes at baseline reversed to AGT. 1-hour glucose concentrations at or above 8.7 mmol/L (157mg/dL) during baseline OGTT had 80% sensitivity to identify those with AGT at 12 months (OR 1.51 [1.20, 1.92], p=0.001). 20 participants had a 24-month OGTT that confirmed preserved insulin secretion.

Conclusion: ETI may improve glucose tolerance in adolescents with CF by preserving insulin secretion. 1-hour glucose during the OGTT helps to detect risk for AGT after ETI treatment.

Keywords: CFTR; Cystic Fibrosis; Elexacaftor/tezacaftor/ivacaftor; adolescents; glucose tolerance; oral glucose tolerance testing.