The effects of insulin-like growth factor I (IGF-I) and insulin on glucose metabolism were compared in awake, chronically catheterized rats with chronic renal failure (CRF) and sham-operated, pair-fed controls. In control rats, IGF-I (5 micrograms.kg-1.min-1) and insulin (2 mU.kg-1.min-1) infusions produced similar twofold increases in total body glucose uptake from fasting values under euglycemic conditions (euglycemic clamps). Total body glucose uptake during euglycemic IGF-I clamps at 5 and 10 micrograms.kg-1.min-1 was not different between CRF and control rats. Total body glucose uptake during euglycemic insulin clamps at 2 and 4 mU.kg-1.min-1 was significantly lower in CRF rats compared with corresponding values in control rats. Hepatic glucose production was suppressed by insulin equally but not by IGF-I in both groups. Correction of metabolic acidosis by NaHCO3 partially improved insulin resistance in rats with CRF, whereas an equimolar amount of NaCl had no effect. Thus the capacity of IGF-I infusion to stimulate total body glucose uptake is maintained in CRF rats that are insulin resistant.