A needle inserter, comprising: a needle (110) having a sharp end and an opposite end, the needle being insertable through a base (102)； and a needle protection device, comprising: an inner protection (164)； and an external protection (162) fixedly connected to the opposite end of the needle (110) and movable with respect to the internal protection (164) between a first position, in which the sharp end of the needle (110) is exposed outside the inner protection (164), and a second position, in which the sharp end of the needle (110) is protected by the inner protection (164)； wherein the interaction between parts of the inner and outer protections (162, 164) during or after the proximal displacement of the outer shield (162) from the first position to the second position automatically releases or allows the release of the inner protection (164 ) of its connection to at least one of the base (102) and the fluid connector (126), characterized in that the inner protection (164) comprises a cantilever latch beam (178) connected to the inner protection ( 164) by a latch (186) of the protection, wherein the inner protection (164) is connectable through the cantilever beam (178) to at least one of the base (102) and a connector (126 ) of fluid connectable to the base (102)； and the outer protection (162) comprises a latch (182) of the connector that engages the cantilever beam (178) and prevents radial displacement of the cantilever beam (178) to maintain the connection between the inner protection (164) and the base (102) when the outer protection (162) is arranged in the first position； and when the outer protection (162) is arranged in the second position, the latch (182) of the connector is coupled to the latch (186) of the protection, thereby allowing radial displacement of the latch beam (178) cantilever and avoiding greater proximal displacement of the outer protection (162) with respect to the inner protection (164).Un insertador de aguja, que comprende: una aguja (
