The Alanine and Cori cycles of human metabolism. (A) The Alanine and Cori cycles are methods for peripheral tissues to receive glucose under nutrient limited situations. Gluconeogenic substrates (e.g. alanine and lactate) are released from peripheral tissues and absorbed by the liver to produce glucose. The glucose is then returned to the peripheral tissues for their metabolic requirements. (B) The flux spans for the HM and MM under individual or integrated simulations are shown. The multi-tissue modeling approach has a constraining effect on the HM and MM models (see Table 1). GLC = glucose, ALA = alanine, PYR = pyruvate, LAC = lactate.