Diabetes and obesity are very common in Western society. In spite of their prevalence, our understanding of their molecular basis is rudimentary. Mouse models of obesity and diabetes contribute greatly to a better understanding of how the environmental and genetic causes affect metabolism. Mouse Metabolic Core has developed a set of tools to analyze metabolism in genetically modified mice. The following techniques are now provided as service to the NIDDK investigators. To characterize obesity we analyze body composition in live mice, body temperature, food intake, metabolic rates and diet induced thermogenesis. To study diabetes we perform insulin tolerance, glucose tolerance, 1st phase insulin secretion tests, glucagon, pyruvate and glutamate challenge tests, and conduct euglycemic-hyperinsulinemic clamp. To characterize pancreatic islets function we isolate islets from mouse pancreas, induce type 1 diabetes using STZ and perform transplantation of islets from various sources into NOD scid diabetic mice. We also measure the rates of triglyceride clearance and production, analyze tissue triglyceride content and fatty acid oxidation in isolated muscle, perform hormone clearance tests and measure concentration of major metabolites and hormones in mouse serum.