LEP and obesity due to melanocortin 4 receptor deficiency: Hyperleptinemia caused by obesity is also involved in the occurrence of DN: leptin can stimulate the proliferation of glomerular endothelial cells and glomerular mesangial cells, as well as the proliferation of tubulointerstitial cells and matrix components, by inducing oxidative stress of glomerular endothelial cells, leading to the occurrence of glomerular sclerosis.