Role of Glucagon In Glucose Control in Cystic Fibrosis Related Diabetes

This project is designed to begin to characterize the abnormalities of glucagon secretion in subjects with cystic fibrosis related diabetes along the spectrum of glucose tolerance. This will be a descriptive, cross-sectional and longitudinal cohort study in a sample of children and young adults with CF and a continuum of glucose tolerance compared to healthy age-matched controls.

Cystic fibrosis patients with normal glucose tolerance as well as cystic fibrosis related diabetes as well as control subjects will be admitted to the research unit on three separate occasions to undergo an oral glucose tolerance test, mixed meal tolerance test, and one step hypoglycemic clamp. Cystic fibrosis patients will then return 12 months later to undergo repeat mixed meal tolerance test and hypoglycemic clamp test.

Inclusion criteria

• Diagnosis of CF by clinical or genetic determination
• Normal glucose tolerance or CFRD
• Subjects routinely taking systemic or inhaled glucocorticoids on stable regimen are eligible

Exclusion criteria

• Subjects with active pulmonary infection requiring supplemental doses of corticosteroids
• Use of any oral diabetes medications
• Subjects who are pregnant/lactating
• Subjects with poor compliance with pancreatic enzyme replacement therapy

Control Subjects:

Approximately 10 control subjects who are matched for age, gender, are expected to be enrolled in the study. Non-CF subjects must be >12 years old, in good health and not taking any medications or have any medical problems the doctor feels would prevent the subject from completing the study and have BMI between 15-85% for age and gender. Control subjects whose fasting blood glucose is found to be >110 mg/dL will not be continued in the study.