INS and obesity due to melanocortin 4 receptor deficiency: Lactobacillus can regulate the balance of serum lipids, glucose, etc. through bile acids, benzene derivatives, organic acids, and others to promote lipid absorption, maintain intestinal barrier function transport, and conduct endocrine function signals; Clostridium can affect intestinal permeability through bile acids, lipids, etc. and activate the intestinal-brain-hepatic nerve axis to regulate glucose balance; Rothia can provide energy to the colonic epithelium by producing SCFAs and participate in the progression of obesity, insulin interference, and T2DM.