Apparatus with at least one test field (26) of test strips (20), to measure concentrations such as blood sugar, has a code carrier (24) with an electronic memory (30) to store the coded information at the test strips (20) or package relating to them. A data processing unit (32) scans the code carrier (30) for transfer to the meter (10). The data processing unit (32) is controlled by the meter (10) through variable control information.