In one embodiment a diagnostic test unit for analysing body fluid is provided which utilises a leaf spring (6) in combination with a seal (8), located in at least one section of a supply chamber opening, to shield the test tape (3) or test strips stored in the supply chamber (2) from the environment outside the chamber (2). The leaf spring (6) is applied directly over the opening of the storage chamber (2), closing it to the outside environment, after the chamber has been loaded with test tape or test strips and drying agent. The closing leaf spring (6) is sealed onto a face on the chamber which borders the opening and at least one section of the face is formed by a seal. The test tape or strips (3) exit through a gap between the closing leaf spring and the seal.
