A small Italian trial tested the accuracy of two popular blood glucose monitors at an altitude of nearly 10,000 ft. The Glucometer Elite II and the LifeScan One Touch II were tested on six type 1s who all had good glycemic control and no diabetes-related complications. The readings from the meters were compared to the results from venous blood samples. The findings were reported in the January issue of Diabetes Care.
Although both meters performed well at sea level and at a moderately high altitude, their margins for error seemed to increase at a higher altitude. At sea level, both meters tended to under-estimate glucose levels. At almost 10,000 ft, the Glucometer tended to over-estimate glucose levels, especially for the low to intermediate (<100 to 200 mg/dl) range. This tendency to over-estimate may be a problem, especially if the person who is testing is experiencing low blood sugars. On the other hand, at a higher altitude, the LifeScan meter tended to under-estimate blood glucose levels, especially those in the high range.
The researchers conclude that a decrease in pO2* (partial pressure of oxygen) could cause the meters to under-estimate blood glucose levels and an increase in atmospheric pressure could cause the meters to over-estimate blood glucose levels. Despite such minor tendencies toward over or underestimation at higher altitudes, both the LifeScan One Touch II and the Glucometer Elite II performed well overall.
The findings may have ramifications for diabetic athletes, professional and amateur alike, who enjoy higher-altitude sports such as skiing and hiking.
* The normal pO2 of arterial blood is about 100 mmHg. The pO2 of room air in an atmosphere of 760 mmHg is about 160 mmHg.