As a common pathological feature among metabolic diseases, including obesity, non-alcoholic fatty liver disease (NAFLD), and type 2 diabetes mellitus (T2DM) (Tilg et al., 2017), insulin resistance decreases the metabolic response of target cells to insulin, resulting in an impaired ability of circulating or injected insulin to decrease blood glucose levels at the whole-organism level (Reaven, 2005). The gene discussed is INS; the disease is obesity due to melanocortin 4 receptor deficiency.