ABSTRACT
AIMS: The diagnosis of cystic fibrosis-related diabetes (CFRD) faces several challenges. We propose a novel screening algorithm to alleviate the burden of cystic fibrosis (CF). METHODS: Through a retrospective cross-sectional single-centre study, HbA1c and HOMA2 indices were assessed in multiple models as alternative diagnostic tools from OGTT data. We sought to establish specific thresholds for CFRD screening with oral glucose tolerance test (OGTT) as gold standard. We evaluated various straightforward or sequential approaches, in terms of diagnostic accuracy while also quantify the potential reduction in OGTTs through these different methods. RESULTS: HOMA indices were recovered in 72 patients. We devised a composite index that combines HbA1c and HOMA-B: Diabetes Predicting Index in cystic fibrosis (DIPIc) = (HbA1c(%) × 3.455) - (HOMA-B(%) × 0.020) - 19.294. This index yields the highest screening accuracy according to receiver-operating characteristics curves. Using a stepwise algorithm that incorporates DIPIc decreases the requirement for annual OGTTs. A CFRD exclusion cutoff less than -1.7445 (sensitivity 98 %), in conjunction with a CFRD diagnostic threshold greater than 0.4543 (specificity 98 %) allows for 71 % OGTT sparing. CONCLUSION: The composite index DIPIc is a suitable, less invasive screening method for CFRD, which enables to avoid many OGTTs.
Subject(s)
Cystic Fibrosis , Diabetes Mellitus , Glucose Intolerance , Humans , Glucose Tolerance Test , Glycated Hemoglobin , Cystic Fibrosis/complications , Cystic Fibrosis/diagnosis , Blood Glucose , Retrospective Studies , Cross-Sectional Studies , Diabetes Mellitus/diagnosis , Glucose Intolerance/diagnosisABSTRACT
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.
