Because of its unique metabolism, glucose illustrates the advantages and limitations of stable isotopic tracers for in vivo studies. The present review describes the application of stable tracers in studies of glucose metabolism. The natural abundance of these tracers requires that careful attention be given to the dose of the tracer and the impact of the background abundance on measurements. The consequence of the natural variation of 13C abundance on measurements in vivo is described, as is the application of multilabeled molecules to estimate kinetics and intrahepatic precursor pool enrichments. The final section outlines recently described methods of estimation of gluconeogenesis.