By: Sharon Kellaher
This installment in the meters, strips and glucose testing series discusses temperature and humidity and their effects on meter and strip functioning. For comments, contact Sharon Kellaher at (800) 234-1218.
As we approach spring, we say goodbye to cold mornings and waking up to a glucose meter that won’t work if your house gets too chilly. But soon will come summer, with its heat and humidity that can foul up our meters as well. And during any season, those of us who hike or ski at high altitudes can lose our meter function.
Some meters display warnings to tell you when they are too hot, cold or humid to function. Others just give inaccurate readings. None has an altitude warning.
Strips are even more susceptible to extreme weather. They like staying at room temperature, out of dampness.
“The chemical reactions the meters perform [to read glucose levels] are affected by both altitude and temperature,” confirms Kris Berg, EdD, a physical education professor at the University of Nebraska at Omaha.
According to Berg and other diabetes experts, all diabetes equipment should be protected from the elements. See the chart below for specifics on your meter.
During a cold-weather activity, Berg advises keeping your meter and strips in a pouch. You should be wearing several clothing layers in the cold, and the pouch should be placed in the middle of those layers. If it’s directly touching the skin, it could get too warm.
Even if you are indoors, your house can easily dip into temperatures too cold for proper meter function. Many meters cannot work below 55 degrees Fahrenheit, a common occurrence on winter nights or in drafty, old houses.
Hot, Humid Weather
To keep the meter and strips cool, use an insulated pouch with an ice pack to carry them. “Don’t place the equipment directly next to the ice,” warns Jane Seley, RN, CDE, of Beth Israel Medical Center in New York City, “or they will get too cold.”
Strips are particularly sensitive to humidity, and the pouch protects against damage. Most manufacturers agree that strips should be kept in their wrapping until the moment they are used.
A 1996 study in Diabetes Care showed that high altitudes cause meters to lose accuracy because of low barometric pressure. Meters were tested at lab-simulated altitudes of 1,000 to 4,000 feet, and most of the meters gave readings that were too low.
Glucose monitoring at high altitudes is not a well-known subject, says Berg. Consultation with the manufacturer and a health care professional should be done before any high-altitude activity.
Most manufacturers have tested their meters up to a certain level. (See the chart below for your meter’s specifications.) Beyond this level, the only information is stories from brave people with diabetes who have ventured this far.
DeAnn Johnson, RN, is a diabetes educator at the Barbara Davis Center in Denver. She often skis and hikes in the Rocky Mountains, up to around 10,000 feet. Johnson says she has never experienced a problem with altitudes, but always recommends keeping everything covered and insulated from the cold.
Serious climbers who have gone much higher than recommended say that at some point the meter will stop working completely, but no one can say exactly where this occurs. If you go beyond your manufacturer’s altitude guidelines without back-up equipment, you could be left with no means of measurement.
Checking the Warning System
If you experience a seemingly strange reading while in extreme weather, a calibration check should be the first step.
Before you go, know your meter, says Seley. Here is a guide to the operating guidelines of your meter.