INSR and obesity due to melanocortin 4 receptor deficiency: IR is a key factor in the development of metabolic diseases such as T2DM, obesity, and cardiovascular diseases, involving multiple molecular mechanisms, particularly dysfunction of the insulin receptor signaling pathway, abnormalities in insulin receptor substrates (IRS), and chronic low-grade inflammation (Samuel and Shulman, 2012; Petersen and Shulman, 2018).