With winter weather approaching, many of us take precautions to handle worsening driving conditions: we install snow tires, pack our trunks with sandbags and ease up on the accelerator when the roads turn slippery.
Are we just as cautious, however, when using our glucose meters in cold weather? Just as it is important to understand how your car behaves in cold weather, it is important to understand how your meter responds to cold temperatures.
How Environmental Conditions Affect Meters
Blood-glucose meters are affected by various environmental conditions: temperature, humidity and altitude. During winter months, colder temperatures can affect the accuracy of blood-glucose test results due to the chemical reaction between the blood sample and the test strip. To avoid inaccurate test results when temperatures are extreme, meters generate error messages instead of test results. These messages are an indication that temperature limits of the meter and test strips have been exceeded.
How to Handle Error Messages
Meter-error messages can be particularly disturbing when you are hiking or camping outdoors in the winter, or anytime that the temperature drops below the operating temperature range of your blood-glucose meter. What do you do?
Vicki, a camper writes, “Once when I was camping with my meter… doing my [blood-glucose test] I got an error message. I panicked until I realized the poor little thing was cold… I put it inside the sleeping bag with me for a few minutes, and then it was okay.”
How to Manage Your Meter While Camping in the Winter
- Meters typically have an operating temperature range well above what you would expect to experience while spending a few hours outdoors. Therefore it is important that they be kept relatively warm. Also, in extremely cold temperatures blood can freeze before the meter is able to process the test results. If you think that you’ll be outdoors for long periods of time, choose one of the newer meters that gives test results in 15 seconds or less.
- Alkaline batteries generally do not do well when exposed to sub-freezing temperatures for long periods. Choose a meter that uses lithium batteries instead of alkaline batteries.
- If you need to perform a test outdoors in bitterly cold weather, huddling with your meter and strips underneath a space blanket may help prevent your blood from freezing before the meter can process the test results.
- Meter users also need to take precautions when using meters in high altitude conditions. Consider using a meter such as the Freestyle, which operates with less dependence on oxygen. For that same reason, it can also be used by people with lower or higher levels of blood hematocrit (such as anemia). According to the 1996 FDA guidelines on meter use, meter results may be inaccurate at higher altitudes due to reduced oxygen concentrations.
What to Look for When Buying a Meter
When buying a meter for use in cold climates, look for a small meter with a small blood-drop size requirement, a wide operating temperature range and a quick test time (see chart).
Although meters, such as the ONETOUCH Ultra, have a wide operating temperature range, none of the meters currently available can operate in below-freezing temperatures, so do not rely only upon the meter’s operating temperature range. If you plan on being outdoors for long periods of time and need to test during that period, carry your meter, strips and insulin in a pouch close to your body. In cold weather, I carry my insulin pump, meter and strips in an accessory case that fits snuggly underneath my layers of clothing, allowing body heat to maintain my equipment and supplies within normal operating temperatures.