It is important to run periodic control tests to ensure that the meter and test strips are functioning and giving reliable results. These tests are strongly recommended: When the meter is new  before using a new batch of test strips  When the cap has been left off of the strip vial, allowing the strips to oxidize When the strips have been stored in an area of extreme temperature and/or humidity When the machine has just been thoroughly cleaned  When test results do not coincide with how you feel  When the test is repeated and the levels are not what is expected When you want to verify that you are performing the test correctly