By: Daniel Trecroci
Whether type 1 or type 2, young or old, all people with diabetes have one thing in common: their blood-glucose meter.
“Your meter travels everywhere with you, extending your health and well-being with each use. You literally trust it with your life—a bond between human and machine rarely equaled,” says diabetes educator Jane Seley, RN, CDE. She adds that the blood-glucose meter is the “single most important thing” in the life of a person with diabetes, both type 1 and type 2.
When looking for the right meter, it’s always important to focus on the essentials:
- Smaller blood samples
- Possibility of using alternate-site testing
However, because a meter is just as individual as the person who uses it, you’ll also want to take factors such as these into consideration:
- The hematocrit range of the meter
- Whether the meter is calibrated for whole-blood or plasma-equivalent results
- Whether the meter allows you to download and manage data that can be sent to your healthcare practitioner
Cindy Onufer, RN, MA, CDE, a diabetes nurse specialist and DIABETES HEALTH’s clinical adviser, says it’s important for the person with diabetes and his or her healthcare provider to discuss all of these factors before choosing a meter.
(On pages 39-41 of this issue, you’ll find a current summary of features for a variety of widely used meters.)
The term “hematocrit” refers to the percentage of red blood cells in a person’s blood. Jean Betschart Roemer, RN, CDE, of Children’s Hospital of Pittsburgh in Pittsburgh, Pennsylvania, explains that if a meter’s accuracy depends on a normal hematocrit, a person who is anemic or very dehydrated could get gross errors in blood-glucose tests. “These conditions could cause the hematocrit to be abnormal,” says Roemer.
Onufer cautions that individuals with anemia (low hematocrit) or a chronic lung disease such as chronic obstructive pulmonary disease (high hematocrit) should not use a meter that depends on a normal hematocrit level. “For example, patients with kidney disease and on dialysis often have anemia, as do many transplant patients.”
Onufer adds that people who have any conditions that affect their red blood count should check with their healthcare team for laboratory results to determine whether their blood-glucose meter system can give accurate results for them.
Calibrated for Plasma or Whole-Blood Readings
Because the two types of calibration systems—plasma and whole blood—differ by approximately 10 percent, it is important to know how to use the results, especially if you are using two meters that are calibrated differently, Roemer explains.
Whole-blood-calibrated meters do give results that are 10 to 12 percent lower than tests from the plasma-calibrated meters, Onufer agrees. This is true even though both systems are measuring glucose in whole-blood samples. The plasma-calibrated systems convert the results to plasma-equivalent values, which are like laboratory results.
Onufer prefers to have one standard of measurement, noting that it is easier for patients and the entire healthcare team to track goals when the plasma-equivalent values are the standard. “Then all self-tests correlate to lab tests. It’s less confusing for patients.”
Her wish is that some day all meters will be calibrated to perform their whole-blood tests to give plasma-equivalent results.
A Memory/Data Management Feature
Onufer ranks this feature very high on her list of priorities. She understands that not all people with diabetes want or need to have software at home to download and analyze their blood-glucose data. However, “all healthcare teams specializing in diabetes care should be able to download every patient’s meter data and work with the patient to understand patterns and make action plans as needed.”
Roemer adds that a date/time memory is also important for anyone who takes insulin. The ability to check past readings can help in calculating carbohydrate-to-insulin ratios, in fine-tuning dosages and averting errors, and in identifying problem patterns.
Onufer notes that the amount of blood required for testing has decreased so dramatically in the last two years that most meters using the newer electrochemical technology require only a 0.3- to 4-microliter blood sample.
“That’s a big change from the 10-microliter samples needed by the reflectance meters,” says Onufer. “From a CDE’s perspective, whatever increases ease and comfort for people with diabetes so they will monitor more frequently is a good thing.”
Onufer stresses that the only way to be successful with pattern management and to reach A1C targets is to check blood-glucose levels more often. She believes that easier-to-use meters with smaller sample sizes have helped a lot in this regard.
“People seem to really like the smaller, tiny systems unless the LCD read-out of results is too small for their vision,” says Onufer. “They seem to want smaller carrying cases with the meters also. Portability is the key for more frequent monitoring. The tools should help people fit diabetes self-care into their active lives.”