Vanadium compounds have been shown to have insulin-like properties in rats and non-insulin-dependent diabetic humans. The purpose of the present study was to examine whether the effects of acute and short-term administration of vanadyl sulfate (VA) on insulin sensitivity also exist in healthy active individuals. Five male and two female participants (age: 24.9 +/- 1.5 years; height: 176.1 +/- 2.9 cm; body mass: 70.1 +/- 2.9 kg) underwent 3 oral glucose tolerance tests (OGTT). The first OGTT was performed to obtain a baseline index of insulin sensitivity (ISI). On the night preceding the second OGTT, participants ingested 100 mg of VS, and the acute effects of VS on ISI were examined. For the next 6 days, participants were instructed to ingest 50 mg of VS twice daily, and a final OGTT was performed on day 7 to determine the short-term effects of VS on ISI. No differences were found in fasting plasma glucose and insulin concentrations after VS administration. Furthermore, ISI after 1 day and 7 days of VS administration was not different compared with baseline ISI (4.8 +/- 0.1 vs. 4.7 +/- 0.1 vs. 4.7 +/- 0.1, respectively). These results demonstrate that there are no acute and short-term effects of VS administration on insulin sensitivity in healthy humans.