IARS1 and type 2 diabetes mellitus: In comparison, the more common type 2 diabetes is characterized by tissue-specific insulin resistance in skeletal muscle, liver, and adipose tissues, as well as molecular defects involving impaired insulin receptor substrate (IRS) phosphorylation, glucose transporter type 4 (GLUT4) transporter translocation, and abnormal signaling networks (e.g., phosphoinositide 3-kinase (PI3K)).