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Your glucose meter is on the table. You insert a new test strip, load a fresh lancet into your lancing device, snap the tiny needle into the side of your finger, and squeeze until a fresh, red dome gathers. You apply the drop of blood to the edge of the strip and watch as your meter counts down to reveal a meaningful number. That number can change the course of your entire day. Or, it could just be a checkpoint that passes by until the next one. But have you ever taken a moment to wonder how this key diabetes technology works?

How your meter measures the sugar in your blood

Blood glucose test strips contain a capillary that sucks the blood up into the test strip. It reaches an enzyme electrode where an electrical current is created. The charge passing through the electrode is proportional to the amount of glucose in the blood sample. So, if your meter reads 90 mg/dL, there are 90 milligrams of glucose in a deciliter of your blood.

Alternative site testing

Fingertips are sensitive because of the high concentration of nerves. To avoid the pain, many people draw blood from other areas. Most blood glucose meters were originally designed to be used with capillary blood taken from a finger prick. Some, including all of the meters we carry, have been approved for alternate site testing (AST), which is blood drawn from areas other than your fingertip, such as your palm or arm. If you are interested in AST, read your meter directions to find out if it’s approved for alternate site testing before attempting to make the change.


It’s important to remember that when you test your blood sugar using any glucometer the result shows you an estimate of the amount of glucose in your blood. The accuracy standard for all meters says that glucose meters must show results that are within 20% of a laboratory standard 95% of the time. Many factors can affect the accuracy of your meter’s results, including: temperature, levels of other substances (such as ascorbic acid) in your blood, traces of other elements on your skin (such as food residue), water, heat, the age of your test strips (check expiration dates), temperature and many more.

Why control solution is important

When you understand the process you can see why control solution is important. Control solution assists you in making sure that the chemicals on the test strips haven’t been damaged. The enzyme on test strips is very sensitive to heat, cold, moisture and direct sunlight. Once test strips are shipped from their factory it is difficult to ensure environmental factors have not affected the enzymes on the test strips. If one is affected, all are in that shipped batch. Use control solution on the first strip you use from a new container to verify that yours are in good condition