Written on August 7, 2023 by Lori Mulligan, MPH. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.
Table of contents
For anyone living with diabetes, the key to avoiding diabetes-related complications such as heart disease, nerve damage, eye problems, kidney disease, and the dangerous onset of hypoglycemia, is to proactively manage blood sugar levels.
When used correctly, blood glucose monitors—small devices that measure and display your blood sugar level—are usually accurate. But occasionally they may be incorrect.
You may be wondering what can cause false high blood sugar readings. Consider these factors that affect meter accuracy and the steps to resolve or prevent the problem.
Throw out damaged or outdated test strips. Store strips in their sealed container. Keep them away from moisture and humidity. Be sure the strips are meant for your specific glucose meter.
Keep your glucose meter and test strips at room temperature.
Wash and dry your hands and the testing site thoroughly with soap and water before pricking your skin. Don't use hand sanitizer before testing. If using alcohol wipes, let the site completely dry prior to pricking.
Fully insert the test strip into the monitor. Replace the monitor batteries as needed. Replace the monitor every 4 to 5 years.
Touch a generous drop of blood to the test strip. Don't add more blood to the test strip after the first drop is applied.
If you're using a testing site other than your fingertip and you think the reading is wrong, test again using blood from a fingertip. Blood samples from alternate sites aren't as accurate as fingertip samples when your blood sugar level is rising or falling
If you are dehydrated or your red blood cell count is low (anemia), your test results may be less accurate.
To provide reliable blood glucose results, even blood glucose systems with high analytical performance require correct handling and appropriate measurement conditions. Inadequate education has been identified as a leading cause of bad self-monitoring blood glucose (SMBG) performance. Thus, patients need appropriate education in the correct performance of SMBG as well as for handling and storage of test strips. Education must also include careful interpretation of blood glucose readings since blind trust in exceptional results may produce wrong and even dangerous treatment decisions.
Blood glucose meters sometimes lose their accuracy without any obvious signs, so you should calibrate your meter regularly.
To calibrate your meter, you need to perform a control solution test. The solution sometimes comes with your meter. If it doesn’t, get in touch with the manufacturer: they’ll usually be happy to provide a control solution for free. To find out exactly how to calibrate your specific meter, consult the instruction manual.
Certain saccharides can falsely elevate the results obtained from point-of-care (POC) glucose meters using the glucose dehydrogenase pyrroloquinoline quinone (GDH-PQQ) enzyme/indicator test method.
The most common methods offered by the medical manufacturers and FDA to prevent falsely elevated blood glucose levels include the following :
In addition to the methods described above to prevent falsely elevated blood glucose levels, clinical analysts suggest that providers also consider the following:
Your results can vary because of natural changes in your blood glucose level. For example, your blood glucose level moves up and down when you eat or exercise. Sickness and stress also can affect your blood glucose test results.
Everlywell offers an at-home HbA1c test (with sample collection at home and sample testing in a lab) that could serve as a periodic complement to your more frequent blood glucose monitoring to help you manage your diabetes.