INS and obesity due to melanocortin 4 receptor deficiency: In obesity, a multiethnic cohort of 632 youth (aged 7–18 years) demonstrated that basal and stimulated MCRI, determined by the ratio between insulin secretion rate and plasma insulin levels at fasting and during a 3‐h OGTT, is lower in Black versus White youth, with similar MCRI levels observed between White and Hispanic youth [35].