Cannula inserter comprising a casing with a distal end, intended to be placed in proximity to the skin of a patient, and an opposite proximal end, a piston fixed at least temporarily by retaining means, drive means designed to exert a propulsion force of the piston in the direction counter to the trigger, and release means intended to release the piston; the inserter additionally comprising a needle fixed to a support; the piston being mounted in the casing in such a way that, once released, it reaches and remains temporarily in a first position, then a second position; the needle and its support also being arranged so as to be able to be driven by the piston in a direction corresponding to the main orientation of the casing, before the piston reaches said first position, and so as to be able to effect an automatic rotation about an axis perpendicular to said main orientation during the movement of the piston between said first position and said second position.