A glucometer, or blood glucose meter, is a portable device that measures the concentration of glucose in a small blood sample, providing a snapshot of the body’s blood sugar level. Individuals managing diabetes rely on this information multiple times a day to make immediate decisions about diet, physical activity, and medication, such as insulin dosing. Since treatment decisions are based directly on the reading, a meter that is not working correctly can lead to serious health complications, making accuracy paramount for effective health management. Ensuring the meter provides reliable results involves checking supplies, controlling the environment, verifying the device, and using proper testing technique.
Daily Pre-Test Preparations
The accuracy of a blood glucose reading begins with the condition of the test strips and the testing environment. Test strips contain specialized enzymes and chemical reagents that react with the glucose in the blood sample. These components are sensitive to environmental factors and time. Using a strip past its expiration date can cause the enzymes to degrade, leading to inaccurate results that may be falsely high or low. Always check the expiration date printed on the vial and discard any strips that have passed it.
It is important to store the test strips and the meter within the manufacturer’s specified temperature and humidity ranges. Extreme heat, cold, or high humidity can damage the chemical integrity of the strip, potentially causing erratic or inaccurate readings. For models that require coding, the unique code on the meter must match the code on the strip vial to ensure the meter’s internal calibration is correct for that specific batch of strips. While many modern meters use “no-coding” technology, verifying the code is a necessary step for older or specific models.
Verifying Meter Function with Control Solutions
Control solution is a liquid containing a known, stable concentration of glucose that is used to check the performance of the glucometer and the test strips. Testing with this solution confirms that the meter’s electronics and the strip’s chemical reaction are working together as intended. The control solution itself is not used to calibrate the meter, but rather to verify its mechanical and chemical accuracy.
A control test should be performed when opening a new box or vial of test strips, if the meter is dropped, or whenever you receive a reading that does not match how you feel. To perform the check, insert a test strip and apply a drop of the vigorously shaken control solution instead of blood. The resulting number displayed on the meter must fall within the specific target range printed on the test strip vial. If the reading is outside of this acceptable range, the meter or the strips may be compromised and should not be used for medical decisions until a repeat test passes.
Technique for Reliable Sample Collection
The user’s technique for collecting the blood sample is a significant factor in preventing inaccurate readings. Before lancing, thoroughly wash your hands with warm, soapy water and dry them completely. Warm water increases blood flow, making sample collection easier. Washing removes any residual sugars or contaminants from food or lotions that could falsely elevate the reading. If soap and water are unavailable, an alcohol wipe can be used, but the site must be completely dry before lancing.
To obtain a clean sample, use the side of the fingertip rather than the pad. Avoid excessive squeezing of the lanced area. Squeezing too hard can mix tissue fluid with the blood, which may dilute the sample and cause a falsely low glucose reading. For maximum accuracy, some experts recommend wiping away the very first drop of blood and testing with the second drop, as the first drop may contain more tissue fluid. Ensure the blood drop is large enough to completely fill the strip’s sample area, as insufficient blood volume can lead to an inaccurate low reading or an error message.
Identifying and Resolving Result Discrepancies
If a blood glucose reading appears implausible, such as an unexpectedly high result when you feel well, a systematic troubleshooting approach is necessary. First, re-test immediately with a new strip after re-washing and thoroughly drying your hands to rule out contamination or a faulty strip. Check the meter’s screen for any error messages, and ensure the strip was fully inserted and the blood sample was adequate.
If the second reading also seems incorrect, perform a control solution test to check the hardware and strip function. If the control test fails to fall within the acceptable range, contact the manufacturer or a healthcare provider, as the meter itself may need replacement. Persistent, unexplainable readings, even after a successful control solution test, require communication with your healthcare team, as they may indicate a physiological issue or a need to compare your meter’s reading with a laboratory-drawn blood test for verification.