- History within the 12 months prior to screening of glucose intolerance (impaired glucose tolerance) or CF-related diabetes (CFRD) as defined by at least one of the following: fasting serum glucose of >= 126 mg/dL on two or more occasions; fasting serum glucose of >= 126 mg/dL plus any casual (previously called random) glucose level >= 200 mg/dL; casual (previously called random) glucose of >= 200 mg/dL on two or more occasions; fasting serum glucose of <= 126 mg/dL but 2-hour post oral glucose load of 140-199 mg/dL (impaired glucose tolerance) on two or more occasions; if a subject meets the criteria for impaired glucose tolerance or CFRD in the screening glucose tolerance test, even if there is no history of impaired glucose tolerance, the subject will not be eligible for the study.