Activated immune cells are obligate glucose utilizers and a large lipopolysaccharide (LPS) IV dose causes severe hypoglycemia. Therefore, study objectives were to use the quantity of glucose needed to maintain euglycemia following an endotoxin challenge as a proxy of immune cell glucose requirement. Fifteen fasted crossbred gilts (30 ± 2 kg) were jugular catheterized bilaterally and assigned one of 2 IV bolus treatments: control (CON; 10 mL sterile saline; n = 7) or LPS-infused + euglycemic clamp (LPS-Eu; E. coli 055:B5; 5 μg/kg BW; 50% dextrose infusion to maintain euglycemia; n = 8). Following infusion, blood glucose was determined every 10 min and dextrose infusion rates were adjusted in LPS-Eu pigs to maintain euglycemia for 8 h. Rectal temperature was increased in LPS-Eu pigs relative to control (39.8 vs 38.8°C, P < 0.01). After 3 h, blood glucose content gradually declined for CON pigs while LPS-Eu glucose levels remained unchanged (P = 0.01). Plasma insulin, BUN, BHBA, and L-lactate were increased in LPS-Eu pigs compared with CON (69, 57, 21, and 60%, respectively; P < 0.05). By 8 h, plasma LPS binding protein was increased 24% in LPS-Eu pigs relative to controls (P < 0.01). Plasma NEFA increased with time in CON pigs, but remained unchanged in the LPS-Eu pigs (P < 0.01). White blood cells, lymphocytes, monocytes, eosinophils, and basophils were decreased in LPS-Eu pigs relative to CON (P < 0.01). Additionally, the neutrophil-to-lymphocyte ratio was increased in LPS-Eu pigs relative to CON (72%, P < 0.01). During the 8 h, 232 ± 16 g of infused glucose was required to maintain euglycemia. If the amount of glucose required to maintain euglycemia can be used as a proxy, then the glucose requirements of an activated immune system are approximately 29 g/h.