MTOR and diabetes mellitus: This article mainly studies the role and regulation of the mTOR signaling pathway in cell growth, metabolism, and aging. mTOR is a protein kinase that can sense energy, nutrients, and stress signals, and it can form two different complexes, namely mTORC1 and mTORC2. These two complexes have different substrates and functions, and are also influenced by different upstream factors. The authors review the molecular composition, regulatory inputs, and cellular outputs of the mTOR signaling pathway, and discuss how to use this knowledge to treat cancer, diabetes, and delay aging.