Combined CFTR modulator therapies are linked with anabolic benefits and insulin-sparing in cystic fibrosis-related diabetes

Aims

Combined CFTR modulator therapies have dramatically altered pulmonary outcomes in patients with cystic fibrosis (CF). Their impact on glucose metabolism requires further investigations. This study aims to evaluate insulin requirements after initiation of combined CFTR modulator therapy in patients with CF-related diabetes (CFRD) and HOMA indices changes in CF patients without diabetes.

Methods

We retrospectively analyzed: 1) the effects of tezacaftor + ivacaftor and elexacaftor + tezacaftor + ivacaftor on FEV₁, weight, BMI, HbA1c, and daily insulin dose, in 17 CFRD patients and 2) the impact of tezacaftor + ivacaftor on HOMA indices in 15 CF patients without diabetes.

Results

Age was 37±12y in the CFRD group (70% men), 88% of whom were homozygous for F508del mutation. Diabetes duration was 15±10y. Median duration of combined CFTR modulator therapy was 16 months (IQR: 4) Thirteen patients received tezacaftor + ivacaftor, of whom 9 were switched to elexacaftor + tezacaftor + ivacaftor. Four patients received elexacaftor + tezacaftor + ivacaftor up front. A decrease in insulin needs was noticed in 88% of patients (0.85±0.3 vs 0.71±0.3U/kg/day; p = 0001). Total daily insulin dose decreased from 50±16 to 44±20U/day (p = 0.017). BMI improved (20.9 (IQR: 1.90) vs 22.1 kg/m² (IQR: 3.70); p = 0.014). HbA1c went from 7.3±1.1 to 7.7±1.6% (p = 0.072). Median age was 22y (IQR: 11) in the CF group without diabetes (67% men), 93% of whom were homozygous for F508del mutation. Duration of combined CFTR modulator therapy was 10±5 months. HOMA-B changes were not significant (129.2 (IQR: 84.8) vs 103.5% (IQR: 66.3) nor were HOMA-S changes (from 94±64 to 95±49%). HOMA-BxS decreased from 112±45 to 104±29% (NS). BMI rose from 21.9±3 to 23.1±3.5 kg/m² (p = 0.047). HbA1c was unchanged (5.0±0.5%). FEV₁ improved in both groups (+11% and + 7% of predicted value; p < 0.001; p = 0.013).

Conclusion

Combined CFTR modulator therapies are correlated with a decrease in insulin doses and positive effects on BMI and FEV₁. HOMA indices did not change on tezacaftor + ivacaftor among CF patients without diabetes.