TFAM and metabolic syndrome: SIRT1 can modulate mitochondrial function, glucose metabolism, and lipids by activating peroxisome proliferator-activated receptor-gamma coactivator (PGC-1a) gene transcription and regulating peroxisome proliferator-activated receptor (PPAR), nuclear respiratory factor (NRF) and mitochondrial transcription Factor A (TFAM), which are closely related to the occurrence of metabolic syndromes, such as insulin resistance [23].