Injector for a subcutaneous insertion set

An injector for transcutaneously placing an insertion needle of a subcutaneous insertion set through the skin of a patient, comprising:

• a barrel having an elongated bore formed therein;
• a plunger slidably received within the bore for movement between an advanced position and a retracted position, the plunger including a support structure for mated slide-fit reception and support of the insertion set in a position with the insertion needle oriented for transcutaneous placement upon movement of said plunger from the retracted position to the advanced position, wherein the plunger is substantially incapable of delivering a fluid from the insertion set upon movement from the retracted position to the advanced position;
• a spring for urging said plunger toward the advanced position;
• and
• a trigger for releasibly retaining the plunger in the retracted position, the trigger being operable to release the plunger for spring-loaded movement with a controlled force and speed toward the advanced position,
• wherein the support structure is removable from the insertion set while maintaining the transcutaneous placement of the insertion needle.