2. AIM 2. Characterization of insulin secretion and insulin sensitivity. Previous studies in adults have described peripheral insulin resistance as a major cause of CF related diabetes, yet studies have not been conducted in children. Studies in adults and children without CF suggest that insulin resistance occurs more frequently in Hispanics. We will measure insulin secretion and insulin sensitivity using the frequently sampled intravenous glucose tolerance test (IVGTT) and the minimal model analysis of Bergman, as modified for children. This specific aim tests the hypothesis that Hispanic children with CF have worse peripheral insulin resistance, but similar insulin secretion when compared to Caucasian children with CF.