Role of Glucagon In Glucose Control in Cystic Fibrosis Related Diabetes

Subjects will be instructed to fast after midnight the night prior to the study. Subjects will be admitted to the research unit on the morning of the test for placement of blood-drawing IV for frequent sampling. Patients will drink 1.75 gm/kg glucose (Glucola) to a maximum of 75 gm. Venous samples for glucose and c-peptide will be drawn from the IV at 0, 30, 60, 90 and 120 minutes. Subjects will be instructed to eat at least 75 gm carbohydrates daily in the week prior to this test.

Subjects will be instructed to fast after midnight the night prior to the study. Subjects will be admitted to the research unit on the morning of the test for placement of blood-drawing IV for frequent sampling. Subjects will consume 6 kcal/kg (6 ml/kg) Boost High Protein Nutritional Energy Drink (Mead-Johnson) over five minutes to a maximum of 360 ml. Venous samples for glucose, glucagon, GLP-1, GIP, and c-peptide will be drawn at -10, 0, 15, 30, 60, 90, 120, 150, 180, 210, and 240 minutes.

All subjects with CF and adult (but not pediatric) controls will undergo one-step hypoglycemic clamp. Subjects will be instructed to fast after midnight the night prior to the study. Subjects will be admitted to the research unit on the morning of the test for placement of blood-drawing IV for frequent sampling and a second IV for infusion of insulin and dextrose.