To study the impact of exercise or fasting and of subsequent glucose supplementation on glucose metabolism in rats, a spectrophotometric method was used to determine peripheral blood glucose; a technique associating ¹H-NMR spectroscopy and cortical microdialysis was also used to observe intra- plus extracellular and extracellular brain glucose variations, respectively. Compared with control animals (204 ± 19 µM in dialysate, n = 10), exercise increased brain extracellular glucose levels to 274 ± 22 µM (n = 8; P < 0.05), whereas fasting induced a drop in glucose levels down to 140 ± 9 µM (n = 8; P < 0.05). After fasting, glucose supplemented by infusion increased glycemia from 7.4 ± 0.4 to 19.9 ± 0.8 mM (n = 10; P < 0.001), as well as extracellular and extra- plus intracellular brain glucose to 263 ± 20% (n = 8; P < 0.001) and 342 ± 28% (n = 8; P < 0.001), respectively, over basal for that group. After exercise, a similar infusion increased glycemia from 7.3 ± 0.3 to 16.8 ± 1.1 mM (n = 10; P < 0.001), as well as extracellular and extra- plus intracellular brain glucose to 178 ± 19% (n = 8; P < 0.001) and 244 ± 20% (n = 8; P < 0.001), respectively, over basal for that group. These results confirmed the existence of a link between glucose level variations in peripheral and cerebral areas but also showed that exercise increased extracellular brain glucose levels despite peripheral hypoglycemia, suggesting a specific regulation mechanism of cerebral glucose metabolism during exercise.