Specific Aim 2: Determine the association between insulin secretion during oral glucose tolerance test (OGTT; from C-peptide modeling) and serum unOC in lean and obese children. Determine the association between insulin sensitivity during OGTT (derived from mathematical modeling) and serum unOC in lean and obese children. Obese children are less insulin sensitive, and in an absolute sense, secrete more insulin. However, we predict that at any given degree of insulin sensitivity, insulin secretion will be lower in obese children, and that this difference will be explained by unOC. unOC will be inversely associated with serum leptin, and will be positively associated with adiponectin and insulin sensitivity.