From Joslin

When you have diabetes, it's vital to make sure you're getting the most accurate reading when checking your blood glucose levels to ensure tight diabetes control. Emmy Suhl, M.S., R.D., C.D.E., at Joslin Diabetes Center, reviews different things that can impact your blood glucose reading and how to avoid them.

Things that Can Affect your Blood Glucose Reading

  • A dirty meter.
  • Outdated test strips.
  • If test strips are not compatible with the meter you're using, results may be inaccurate or no result will be obtained. If the wrong strip is used, it may not even fit into the slot or it may fit, but the meter won’t turn on, Suhl says.
  • Substances left on your hands. For example, if there is a sugary substance on the finger used for lancing, even if it’s a small amount that can’t be seen, a high blood glucose reading can result.
  • Temperature changes (heat/humidity/cold air).
  • Not a big enough blood sample on the test strip.
  • Wet fingers. Fluid mixes with blood and can cause an inaccurate reading.

How to Avoid an Inaccurate Blood Glucose Reading

  • Before using the meter for the first time and then again every few weeks, check your meter using the control solution, Suhl says. Control solution is only good for three months once opened. Label the control solution bottle with the date you open it. Check the date and shake control solution before using. The value the control solution gives should be in the target range printed on the strips container.
  • Make sure strips are not expired. Check the date on the strip container.
  • Make sure code on strip container matches the code on the meter.
  • Wash hands in warm water and dry them off after.
  • Massage hands before checking.
  • Select site on one side of the center of a fingertip. Rotate sites for each check.
  • Apply gentle pressure to lanced finger to help the drop of blood form on the surface.
  • Completely fill the strip target area with blood.

The age of the meter seems to be important too. This may be related to corrosion on the contacts that will transport the information from the test stripes to the meter.

Also do 5 tests in a row with 5 strips and see if the readings are close to the first one taken. If not, call the meter company and ask for a new meter. You got a bad meter if there are wide variations.

If you drop a test strip on the floor, discard it. Test strips left unopened, and exposed to oxygen for a long time, will also give inaccurate readings.