Effect of ambient temperature and humidity on performance of blood glucose meters.

The accuracy of four blood glucose meters (Accutrend, ExacTech Companion, Medisense Companion 2, and Glucometer III) was tested at temperatures ranging from 4 to 44 degrees C (control solutions) and 8 degrees C, 24 degrees C, and 36 degrees C (venous blood) and at humidities of 60% and 80%. Low and high temperatures resulted in a number of statistically significant changes in glucose readings with all meters. However, Accutrend, Medisense Companion 2, and Glucometer III were 100% clinically accurate at all temperatures. With the ExacTech Companion, only 70.8% of control solution and 55.6% of venous blood results were clinically accurate. The main errors were: (1) cold temperatures lowered the result so that euglycaemic levels erroneously read in the hypoglycaemic range and hyperglycaemic levels gave a better than actual result and (2) hot temperatures increased the result whereby hypoglycaemic levels falsely gave a euglycaemic result. Weather conditions at which blood glucose meters may be operated can affect results and potentially lead to errors in clinical decisions.