A blood testing device (10) comprising a proximal end (12) and a distal end (14); an intermediate portion (20) between the proximal end (12) and the distal end (14); a pressure compensation system to regulate the pressure in the intermediate portion (20), and a distal end cap (60) at the distal end (14) comprising a first opening (62) configured to receive a test strip (104). The intermediate portion (20) comprises a proximal end (36) comprising one or more than one opening (44), a distal end (38) of the intermediate portion (20) and, between the proximal end (36) and the distal end (38), comprises a hollow, central chamber (40) surrounded by an outer wall (42).