PPARGC1A and diabetic kidney disease: <i>PPARGC1A</i> rescued macrophage polarization and renal tubular cell fibrosis.<h4>Conclusion</h4>Exosomal miRNA-34a of tubular epithelial cells promoted M1 macrophage activation in diabetic nephropathy via negatively regulating <i>PPARGC1A</i> expression, which may provide a new direction for further exploration of DN treatment.