How to ensure accurate results with Alternate Site Testing (AST)

If you are tired of pricking your fingers to obtain a sample for blood glucose testing, you may have considered using alternate testing sites to give yourself a break. However, many people wonder just how accurate a sample is when it is taken from an alternate site and, based on research, this is certainly a valid concern.

Samples taken from other sites on the body can potentially deliver an inaccurate result. If your testing results are not accurate, you could be putting yourself at risk of severe complications.

Are test results from an alternate site different?

The truth is, different parts of your body require different volumes of blood to function properly.

The fingertips, on the other hand, are the most accurate because they have good blood flow. This means you are getting the most accurate representation of your actual blood glucose level at the time of testing. Unfortunately, it can become painful to continuously test on your fingertips.

When testing from another site, such as the thigh, the palm of your hand, your forearm, abdomen or calf, it is important to know if and whether it differs from your fingertip sample so that you can make the appropriate corrections based on your results.

Fingertips are perfect for blood glucose testing. Glucose arrives at the fingertips more quickly than it does anywhere else in the body. The tips of your fingers contain lots of blood, allowing you to obtain a good-enough sized sample to perform the test. There are lots of nerves in the fingertips that require blood to feed them, ensuring there is always a steady flow of blood to the area.

However, the very reasons the fingertips are ideal for testing also make them a challenge. With so many nerves, there is a strong potential for the area to become sensitized over time. If you are involved in a job where you use your fingertips or if you perform an activity that requires the touch of your fingers, this may be a painful proposition.

How to ensure accurate results with Alternate Site Testing (AST)

While you may have considered alternate site testing, there are some concerns that a blood glucose result from an area of the body other than your fingertip could be inaccurate. If the results you are getting from your tests are not accurate, you could be putting your health at risk by over/underestimating the amount of insulin you need. It may also affect your A1C results, which is the indicator your doctor will use to determine how well your diabetes is being managed.

When using an alternate site for testing blood glucose, follow it up with a finger-prick test to compare. There are some studies that show routine after-meal testing from alternate sites is equivalent to fingertip testing, but it is always best to ensure you are obtaining the most accurate result possible. Furthermore, make sure to follow the AST guidelines provided by your blood glucose monitor manufacturer.  

AST should be performed using a special AST lancing device. These devices have a clear tip and are specially made for testing on areas of the body other than the fingertips. Just as you should not use the AST lancing device on the fingertips, do not use fingertip lancets on alternate sites as the sample you take may return inaccurate results.

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