Oral glucose tolerance test and continuous glucose monitoring to assess diabetes development in cystic fibrosis patients

© 2017 SEEN y SED Introduction Patients with cystic fibrosis (CF) undergo a slow and progressive process toward diabetes. Oral glucose tolerance test (OGTT) is recommended to diagnose impaired glucose levels in these patients. Continuous glucose monitoring (CGM) measures glucose profiles under real-life conditions. Objective To compare OGTT and CGM results in CF patients. Methods Paired OGTT and 6-day CGM profiles (146.2 ± 9.1 h/patient) were performed in 30 CF patients aged 10–18 years. Results According to OGTT, 14 patients had normal glucose tolerance (NGT), 14 abnormal glucose tolerance (AGT), and two cystic fibrosis-related diabetes (CFRD). In 27 patients (13 NGT, 13 AGT, 1 CFRD), CGM showed glucose values ranging from 140 to 200 mg/dL during similar monitoring times (2%–14% with NGT, 1%–16.9% with AGT, and 3% with CFRD). Glucose peak levels ≥200 mg/dL were seen in seven patients (3 NGT, 3 AGT, 1 CFRD). According to CGM, two patients had all glucose values under 140 mg/dL (1 NGT, 1 AGT). Seventeen patients had glucose levels ranging from 140 to 200 mg/dL (10 NGT, 6 AGT, 1 CFRD). Ten patients (3 NGT, 7 AGT) had glucose values ≥200 mg/dL for ≤1% of the monitoring time and one (CFRD) for >1% of the monitoring time. Conclusions OGTT results did not agree with those of the CGM. CGM allows for diagnosis of glucose changes not detected by OGTT. Such changes may contribute to optimize pre-diabetes management in CF patients.