INS and obesity due to melanocortin 4 receptor deficiency: When insulin resistance occurs in the body, the compensatory secretion of insulin will cause hyperinsulinaemia, resulting in a series of pathophysiological changes, such as pancreatic islet function impairment, increasing nutrient consumption and hyperlipidemia, cardiovascular damage, and finally leading to a variety of metabolic diseases, such as diabetes mellitus, obesity (Templeman et al., 2017) and diabetic cardiomyopathy (Jia et al., 2016).