The present invention is directed to a cannula insertion device (101, 201) and related methods, the device comprising a cannula (5, 105) including a base, a needle (3, 103) disposed in the cannula (5, 105), a plunger apparatus (17, 18) adapted to advance the cannula (5, 105) with the needle (3, 103) from a retracted position to an extended position and a spring (22, 117) adapted to withdraw the needle (3, 13) automatically from the cannula (5, 105) thereafter.