The Overarching Aim of the Yale MPMOD Phenotyping Core is to provide extramural investigators access to the unique metabolic phenotyping services provided by the Yale MPMOD at a fair and reasonable price, and empower them to characterize the impact of their genetically manipulated mouse models of diabetes and obesity on key metabolic parameters and whole body and tissue specific intracellular metabolic fluxes using state-of- the-art stable and radio-labeled isotope methodology. The Specific Aims of the Yale MPMOD Phenotyping Core are: 1) To provide the scientific community access to standardized, high quality, unique metabolic phenotyping services currently available at the Yale MPMOD at a fair and reasonable cost, 2) To continue to develop novel stable isotope GC-MS, LC-MS/MS and NMR methods to metabolically phenotype whole body and intracellular metabolism in awake mice, and 3) To participate and collaborate with the National Consortium of MPMODs and the MPMOD Coordinating Unit to maintain a national database of metabolic phenotyping data in mouse models of obesity and diabetes. It is anticipated that the results generated by the Yale MPMOD will lead to a better understanding of the pathophysiology of diabetes and obesity and their related metabolic complications and lead to new therapies. Ultimately, the insights generated from in vivo metabolic phenotyping in mouse models will facilitate the development of precision medicine approaches targeting metabolic pathophysiology and its downstream complications.