Usually every 3 days. If you are referring to the plastic catheter tube that delivers Insulin from the pump, and is inserted under the skin --- then this Insulin pump site should be changed in most patients every 3 days. Leaving this in longer can lead to lipodystrophy (fat pad) which prevents effective Insulin absorption, and can also lead to skin infections.
Site change every 3d. For someone using an Insulin pump the site where the Insulin goes into the body using an infusion set needs to be changed every three days. It is recommended that the Insulin reservoir in the pump that stores the Insulin is changed with every other site change which is then on average every six days.