Therefore, in trying to tease out the relationships among MCRI (using the hyperinsulinemic‐euglycemic clamp), fasting insulin concentrations, and β‐cell function (using the hyperglycemic clamp), we examined the following: 1) MCRI in youth with obesity across the glucose tolerance spectrum from normal glucose tolerance (NGT) to IGT to type 2 diabetes; 2) racial and ethnic contrast in MCRI; and 3) the metabolic and adiposity correlates of MCRI by race and ethnicity in youth with obesity. Here, INS is linked to obesity due to melanocortin 4 receptor deficiency.