Electrically driven metal-insulator transition (MIT) in vanadium dioxide (VO2) is of interest in emerging memory devices, neural computation, and high-speed electronics. We report on the fabrication of out-of-plane VO2 metal-insulator-metal structures and reproducible high-speed switching measurements in these two-terminal devices. We have observed a clear correlation between the electrically driven ON/OFF current ratio and the thermally induced resistance change during MIT. It is also found that sharp MIT could be triggered by the external voltage pulses within 2 ns at room temperature and the achieved ON/OFF ratio is greater than two orders of magnitude with good endurance.