MTOR and type 2 diabetes mellitus: A drug used for the treatment of type 2 diabetes (T2D), metformin, is able to attenuate insulin resistance or improve insulin receptor sensitivity through activation of adenosine monophosphate-activated protein kinase (AMPK) signaling, and other pathways, including various AMPK-independent mechanisms, such as affecting mitochondrial function, restoring redox homeostasis, and regulating several other signals, including mechanistic target of rapamycin (mTOR), sirtuin 1, and fructose-1,6-bisphosphatase 1 [180].