A retractable needle catheter insertion device is provided with a cannula and a needle positioned within the cannula to assist with insertion of the cannula. After insertion of the cannula into a patient, the needle can retract into a protective sleeve that contains the needle in order to reduce the chance that a medical practitioner will be inadvertently stuck by a used needle. The needle is carried by a needle support that is slidably disposed within the sleeve. A spring biases the needle support and needle toward a retracted position, and the device also includes an activation hub that works in conjunction with the needle support to control retraction of the needle. The retraction may be activated manually by the medical practitioner or may be activated automatically. A modular system and method of manufacturing is also provided in which catheters having either manually or automatic retraction can be manufactured using common parts.