To test the hypothesis that glucose metabolism is altered by iron deficiency, rates of glucose turnover and oxidation were assessed concurrently with the metabolic rate (VO2) in iron-deficient anemic rats and in normal rats at rest. Male Sprague-Dawley rats, 21 days old, were fed a diet containing either 6 mg iron/kg feed (iron-deficient group) or 50 mg iron/kg feed (iron-sufficient control group) for 3-4 wk. After dietary treatment the iron-deficient group was anemic, with hemoglobin levels of 5.8 +/- 0.2 g/dl, compared with 13.8 +/- 0.4 g/dl for controls. To study glucose metabolism, rats received a 90 min primed-continuous infusion of [6-3H]-and [U-14C]glucose via an indwelling jugular catheter. Serial blood samples were removed from a carotid catheter for determination of glucose concentration and specific activity. Expired air was monitored for VO2, VCO2, and 14CO2. The VO2 (ml X kg-1 X min-1) of iron-deficient rats was 20% higher than controls. Iron-deficient rats had a greater rate of glucose turnover (94 +/- 4 vs. 52 +/- 3 mumol X kg-1 X min-1) and a greater glucose recycling rate, even when normalized to VO2. Despite a higher blood glucose concentration (5.5 +/- 0.6 vs. 4.1 +/- 0.1 mM), the metabolic clearance rate was greater in iron-deficient animals (18 +/- 1 vs. 13 +/- 1 ml X kg-1 X min-1).(ABSTRACT TRUNCATED AT 250 WORDS)