INS and obesity due to melanocortin 4 receptor deficiency: The booming population of obesity around the globe is inevitably contributing to the increase in the prevalence of T2DM, which is also a chronic and overgrowing disease occurring when the body fails to produce enough (or any) insulin or cannot effectively use the insulin it produced, inducing elevated blood glucose (hyperglycemia) as a primary manifestation, ranking as one of the fastest-growing global health emergencies of this century (5).