Cystic fibrosis-related diabetes is a late cystic fibrosis (CF) associated comorbidity whose prevalence is increasing sharply lifelong. Guidelines for glucose metabolism (GM) monitoring relies on oral glucose tolerance test . However, this test is neither sensitive nor specific.

The aim of this study is to compare sensitivity and specificity of different methods for GM monitoring in children and adolescents with CF.

Continuous GM system (CGMS) will be used as the reference method. Results will be compared to those of oral glucose tolerance test (OGTT), intravenous glucose tolerance test (IGTT), homeostasis model assessment index of insulin resistance (HOMA-%IR) , homeostasis model assessment index of beta-cell function (HOMA-%B) and HbA1C dosage (glycated haemoglobin A1C). Patients will be classified into three groups according to CGMS: normal glucose tolerance, impaired glucose tolerance and diabetes mellitus.

Inclusion Criteria:

• Subjects with confirmed diagnosis of Cystic Fibrosis with a sweat chloride > 60 mmol/L.
• Subjects will be aged between 10 and 18 years with at least one class 1 or 2 Cystic fibrosis transmembrane conductance regulator (CFTR) mutation.
• Subjects will be pancreatic insufficient.
• Subjects must have a forced expiratory volume 1 (FEV1)> 40 % of predicted normal for age, sex and height at the screening visit.
• Stable CF disease as judged by the investigator

Exclusion Criteria:

• Subjects with glucose intolerance abnormalities
• Subjects with pulmonary exacerbation within 4 weeks before screening
• History of lung or hepatic transplantation or awaiting transplantation