A cassette containing cartridges for sampling blood from a patient. The cassette includes a container for storing a plurality of cartridges and at least one cartridge in the container. The cartridge includes a cartridge case and a lancet. The lancet has a tip and is housed in the cartridge case. The lancet can be driven to extend the tip outside the cartridge case for lancing the skin of the patient to yield blood. The container has a compartment that contains at least one cartridge. A cartridge from the compartment can be loaded onto a glucometer that drives the lancet in the cartridge to lance the skin of a patient.