Performance and Patient Acceptance of a Commercially Available Beverage as Compared to an Oral Glucose Solution for Oral Glucose Tolerance Tests in Cystic Fibrosis (CF) Patients Who Are Screened for CF-related Diabetes.

Rationale: Cystic fibrosis (CF) is an incurable genetic disease that affects the pulmonary system, digestive system, reproductive system and the sweat glands. 85 percent of patients with cystic fibrosis have pancreatic insufficiency, more than half of whom will develop CFRD. CFRD affects patients nutritional state and is associated with a decline in lung function and decreased longevity. Because early treatment with insulin can reverse some of this decline and mortality, CF patients are screened yearly for CFRD using an oral glucose tolerance test (OGTT). During an OGTT patients have to drink a solution of 75 grams of glucose in water and blood glucose levels are measured after 0 minutes and 120 minutes. Drinking the glucose solutions is experienced by patients as uncomfortable, as it causes nausea and sometimes even leads to vomiting. Therefore, some patients do not want to undergo the OGTT which results in patients getting diagnosed in a later stadium. Objective: To compare the performance of a glucose tolerance test ("AATT") with a commercially available beverage to the results of the conventional OGTT with respect to diagnosing IGT and CFRD in patients with CF. Study design: Randomized crossover trial Study population: Adult cystic fibrosis patients from the outpatient of CF-centre Amsterdam; 10 patients with CFRD who are not fully insulin dependent and 10 patients who have exocrine pancreatic insufficiency but no known CFRD. Intervention (if applicable): The groups will be undergoing both the oral glucose tolerance test with the standard glucose solution (OGTT), as the oral glucose tolerance test where the glucose solution is replaced by commercially available beverage (AATT). Main study parameters/endpoints: Serum glucose levels at 120 minutes after ingestion of either the standard glucose solution or the commercially available beverage. Nature and extent of the burden and risks associated with participation, benefit and group relatedness: Patients who h