Thread: Meters
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Old 07-05-2009, 09:00 AM
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Default Altitude and Meters

This is probably more than you wanted to know about meters and altitude, but yes, it can affect them just as temperature extremes (hot or cold) can:

http://www.liebertonline.com/doi/abs...ournalCode=dia

Effect of High Altitude on Blood Glucose Meter Performance

"Diabetes Technology & Therapeutics. December 2002, 4(5): 627-635
Participation in high-altitude wilderness activities may expose persons to extreme environmental conditions, and for those with diabetes mellitus, euglycemia is important to ensure safe travel. We conducted a field assessment of the precision and accuracy of seven commonly used blood glucose meters while mountaineering on Mount Rainier, located in Washington State (elevation 14,410 ft). At various elevations each climber-subject used the randomly assigned device to measure the glucose level of capillary blood and three different concentrations of standardized control solutions, and a venous sample was also collected for later glucose analysis. Ordinary least squares regression was used to assess the effect of elevation and of other environmental potential covariates on the precision and accuracy of blood glucose meters. Elevation affects glucometer precision (p = 0.08), but becomes less significant (p = 0.21) when adjusted for temperature and relative humidity. The overall effect of elevation was to underestimate glucose levels by approximately 1-2% (unadjusted) for each 1,000 ft gain in elevation. Blood glucose meter accuracy was affected by elevation (p = 0.03), temperature (p < 0.01), and relative humidity (p = 0.04) after adjustment for the other variables. The interaction between elevation and relative humidity had a meaningful but not statistically significant effect on accuracy (p = 0.07). Thus, elevation, temperature, and relative humidity affect blood glucose meter performance, and elevated glucose levels are more greatly underestimated at higher elevations. Further research will help to identify which blood glucose meters are best suited for specific environments."

http://care.diabetesjournals.org/content/28/5/1261.full

Performance of Glucose Dehydrogenase–and Glucose Oxidase–Based Blood Glucose Meters at High Altitude and Low Temperature

"Blood glucose meters using the enzyme glucose oxidase (GO) have been proven unreliable at high altitude. A new test strip technology, based on the oxygen-insensitive enzyme glucose dehydrogenase (GD), has been utilized by some manufacturers.

"Five plasma-calibrated blood glucose meters were evaluated in this study, four glucose dehydrogenase based (GD1: Precision Xtra; GD2: Ascensia Contour; GD3: Accu-Chek Compact; and GD4: Freestyle) and one glucose oxidase based (GO1: OneTouch Ultra), with capillary blood samples from one of the investigators.

"First, all meters were tested in a hypobaric chamber at simulated altitudes (at 20°C in chronological order with ∼8-min intervals) of 0, 4,500, 2,500, and again 0 m above sea level, with normal (∼5.8-mmol/l) and high (∼16.5-mmol/l) plasma glucose values (n = 6 at all conditions). At 4,500 and 2,500 m altitude, the glucose oxidase-based meter (GO1) overestimated plasma glucose values by 15 ± 0.1% (mean ± SD) at the normal blood glucose level and 6.5 ± 0.5% at the high blood glucose level, as compared with the readings at 0 m.

"Comparatively, three glucose dehydrogenase–based meters overestimated readings of normal and high blood glucose levels (GD1 by 6.5 ± 0.2 and 1.5 ± 0.7%, GD3 by 3.7 ± 0.1 and 3.5 ± 0.4%, and GD4 by 0.8 ± 0.2 and 0.8 ± 0.4%, respectively). The fourth, GD2, underestimated readings of normal and high blood glucose levels by 1.9 ± 0.2 and 4.2 ± 0.9%, respectively.

"In addition, three glucose dehydrogenase–based meters (GD1, GD2, and GD3) were tested with blood at up to 5,895 m above sea level during the ascent of Mount Kilimanjaro, Tanzania. In the presence of both high altitude and low temperature, the meters diverged from each other. At the summit, 5,895 m above sea level, the readings of the investigator’s plasma glucose concentration were 2.8, 11.9, and 21.0 mmol/l (GD1, GD2, and GD3, respectively).


"In this study, all four glucose dehydrogenase–based meters performed better than the glucose oxidase–based meter at high altitude, as hypothesized.

"In conclusion, people with diabetes who intend to participate in activities at high altitude or, in particular, at low temperature, should be informed that blood glucose meters may give totally unreliable false low or high readings."

This deals with a change in the chemicals in the test strips which make it possible for the meter to read the blood drop. I believe most to all meters are now using the newer system, glucose dehydrogenase method.

http://www.diabetesselfmanagement.co..._the_altitude/

"I lived in Leadville, Colorado (10,000 feet) and worked at the hospital there. We would frequently have companies come in to do tests on new glucose monitoring strips because they had to prove that the strips worked at altitiude. If we would let them poke our fingers several times we would receive a stipend in cash.

"When I moved to that elevation from about 4000 feet, I had to increase my basal insulin a couple of units."

Posted by MR | Mar 14, 2007 at 1:52 pm

http://web.archive.org/web/200702031...-July-2005.pdf

This Diabetes Health Meter Review is 4 years old, but it gives you an idea of the altitude limit on some of the meters on page 2.


Kathy

Adding here-altitude information on ReliOn Micro from the online owners' guide:

http://www.relion.com/content/diabet...cro_Manual.pdf

Page 71

Altitude (up to) 10,000 feet

Last edited by We Hope; 07-05-2009 at 09:24 AM. Reason: removing non-meter material for Answers section