Taken together, as a chronic metabolic disease, T2DM is closely related to many unhealthy lifestyle habits including obesity caused by excessive eating; the abnormal effective connectivity between the fusiform gyrus and the lingual gyrus and MFG may contribute to the reduced ability to control food intake and abnormal eating habits in T2DM patients, which is manifested as metabolic disturbance such as lipids, glucose, and insulin. Here, INS is linked to obesity due to melanocortin 4 receptor deficiency.