This proposal is focused on the identification and biological validation of the metabolic pathways and key regulatory genes that control insulin sensitivity in Type 2 diabetes mellitus (T2DM). We are focusing on skeletal muscle because it is quantitatively the most important tissue involved in maintaining glucose homeostasis under insulin-stimulated conditions and it is a major site of insulin resistance in T2DM. Our central hypothesis is that alterations in insulin signal transduction to glucose transport contribute to the profound impairment in whole body glucose homeostasis and T2DM pathogenesis. Identification of the defects in T2DM can lead to the development of new therapeutic strategies to prevent and cure this disease. The proposal is divided into two main objectives: We will apply: 1) target identification platforms including microarray, proteomics and bioinformatics to identify dysregulated genes in normal glucose tolerant versus T2DM subjects or genetically modified model systems and 2) functional genomics to assign a physiological role of the identified targets in Aim 1 using cellular and whole-body approaches. We will focus on the mitogen-activated protein kinase family, the energy-sensing enzyme AMP-activated protein kinase, and the lipid intermediate metabolizing enzyme diacylglycerol kinase delta. Our previous work indicates that these candidates play a role in the regulation of glucose metabolism, triglyceride storage, and energy homeostasis.