8. All patients will have random blood glucose testing per CF Foundation guidelines. If a patient has previously undiagnosed cystic fibrosis related diabetes (CFRD) with or without fasting hyperglycemia (FH), he/she will be treated with insulin for a minimum for 3 months prior to study enrollment. Patients in all other glucose tolerance categories will be allowed to participate in the study Also, patients previously treated with insulin will be allowed to participate if HgbA1C is < 8.5%. If not, the PI will adjust insulin and maximize glycemic control for 3 months before study entry. Any patient who develops CFRD with or without FH will be continued in the study only if he/she will agree to insulin therapy. If a patient refuses insulin therapy, he/she will be discontinued from the study. Patients will continue to be screened for glucose intolerance by measuring random blood glucose and HgbA1C.