The invention relates to a portable control device for monitoring the administration of doses by a diabetic. The control device is arranged in conjunction with a portable dosage unit having a body and an injection member designed to deliver the dose to the diabetic and attached to the body of the portable dosage unit. The dosage unit has a removable cap over the injection member. The control device is provided in the cap and is movable together with the cap. The control device comprises a sensor arranged to detect the removal of the cap from over the injection member and connected to an indicator of the control device for showing if the cap has been removed from over the injection member for administering insulin.