Glucose Tolerance in Children With Cystic Fibrosis

Study Overview
=================
Brief Summary
-----------------
The aim is to describe the association of glucose tolerance measured with three different tools (continuous glucose measurement system - CGMS, oral glucose tolerance testing - OGTT and optional intravenous glucose tolerance testing -IVGTT) with parameters out of lung function and anthropometric parameters in patients with cystic fibrosis.

Detailed Description
-----------------
Patients with cystic fibrosis (CF) with progressing disease are developing a glucose tolerance which resembles the metabolic state of a diabetic patient because of increasing impairment of endocrine pancreatic function. The prevalence of this diabetic metabolic state is increasing with age, reaching around 20% at the age of 20 years. Over the last decade, research has already highlighted the negative influence of cystic fibrosis related diabetes (CFRD) on morbidity and mortality after the diagnosis of this condition. As the deterioration in nutritional status and lung function can already be noticed 2-6 years before the onset of CFRD, the importance of early diagnosis in glucose abnormalities and its treatment therefore is crucial. The currently used method to evaluate altered glucose metabolism in patients with CF is an annual oral glucose tolerance test (OGTT) with the glucose value after 120 min after oral ingestion of glucose-fluid as reference. This method may detect CFRD much later than we see deterioration of lung function and weight loss. This deterioration and the mortality in CF is related to CFRD. An alternative diagnostic tool that has gained increasing attention and that is already routinely used in pediatric patients with diabetes mellitus type I is the continuous glucose monitoring system (CGMS) which was shown to be much more sensitive in detecting glucose abnormalities. To assess pancreatic endocrine dysfunction - the pathophysiologic cause for glucose intolerance - intravenous glucose tolerance testing (IVGTT) is the gold standard. The investigator's aim is to describe the association of glucose tolerance measured with three different tools/assessment procedures (CGMS, OGTT and optional IVGTT) with lung function and anthropometric parameters.

Official Title
-----------------
Glucose Tolerance and Its Clinical Impact in Children and Adolescents With Cystic Fibrosis

Conditions
-----------------
Glucose Intolerance, Cystic Fibrosis

Intervention / Treatment
-----------------
* Other: Diagnostics for glucose tolerance with 3 different methods.


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Patients with confirmed cystic fibrosis aged between 10-20 years, under medical treatment at the University Children's Hospital Basel UKBB and at the University Children's Hospital, Inselspital Bern Exclusion Criteria: Patients being under medical treatment with systemically administered glucocorticoid drugs or intravenously administered antibiotic treatment within 6 weeks before glucose tolerance testing. Patients with acute pulmonary exacerbation, defined by a pediatric pneumologist

Ages Eligible for Study
-----------------
Minimum Age: 10 Years
Maximum Age: 20 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------

Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Patients with Cystic Fibrosis<br>Patients between 10-20 years of age with genetically determined cystic fibrosis followed at the university children's hospital Basel and university children's hospital Kinderklinik Bern, Switzerland. All patients will get the diagnostics for glucose tolerance with 3 different methods (CGMS, OGTT and optionally IVGTT). | Other: Diagnostics for glucose tolerance with 3 different methods.<br>* A 7-day course of subcutaneous continuous glucose monitoring system (CGMS). An oral glucose tolerance test done within the 7 day period of CGMS. Optionally a intravenous glucose tolerance test done within the 7 day period of CGMS.<br>|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| % time spent above 8mmol/l, the area under the curve and the mean glucose value (in mmol/l) | These measurements will be gained out of the 7 day CGMS-course (continuous glucose monitoring system). | Beginning at day 1, lasting 7 days | 
| The glucose values given in mmol/l after 30', 60', 90' and 120 minutes during OGTT. | Standard oral glucose tolerance test. | Within the 7 day course of CGMS | 
| First phase insulin secretion and second phase insulin secretion out of IVGTT (intravenous glucose tolerance test). | Standard intravenous glucose tolerance test. | Within the 7 day course of CGMS | 
| FEV1% (forced expiratory volume at one second) out of the lung function testing |  | Within 3 months of the 7 day course of CGMS | 
| Lung clearance index |  | Within 3 months of the 7 day course of CGMS | 
| BMI-SDS (standard deviation score). |  | At day 1 of the CGMS course | 
| HbA1c |  | Within the 7 day course of CGMS | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Comparing the performance between CGMS and OGTT related to clinical parameters. | The investigators compare the fit of a linear regression between the % time above 8mmol/l (out of CGMS) and the lung clearance index (LCI) with the fit of a linear regression of the 120min glucose value (out of OGTT) and the LCI. The same analysis will be performed comparing the fit of a regression between the % time above 8mmol/l (out of CGMS) and the FEV1% (out of lung function) with the fit of a linear regression of the 120min glucose value (out of OGTT) and the FEV1%. Finally, the same analysis will be performed comparing the fit of a linear regression using the % time above 8mmol/l (out of CGMS) and the BMI-SDS with the fit of a linear regression of the 120min glucose value (out of OGTT) and the BMI-SDS. | 7 days | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
children, cystic fibrosis, glucose intolerance, continuous glucose measurement