Testing blood sugar: First or second drop?
When testing your blood sugar, do you use the first drop of blood or the second?
We teach patients to wash their hands with soap and water, dry them, and then test their blood glucose using the first drop. We advise that if the person isn't able to wash his or her hands with soap and water, then the second drop may be used. However, I've heard some patients tell me that they were instructed to use the second drop of blood, even after washing hands with soap and water.
Monitoring your blood sugar is essential to managing diabetes and helps you to make decisions related to diet, exercise and medication. So, what is the "right way" to test your blood glucose?
A February 2011 article in the American Diabetes Association's journal, "Diabetes Care," details a study that investigated whether capillary glucose concentrations, as measured in the first and second drops of blood, differed by 10 percent or more compared with a control capillary glucose concentration in the following situations:
- Without washing hands
- After handling fruit
- After washing the fruit-exposed fingers
- During the application of different amounts of external pressure around the finger (squeezing).
The conclusion of this study, which included 123 participants, is: "The first drop of blood can be used for self-monitored glucose testing, but only after washing hands. If washing hands is not possible and they are not visibly soiled or exposed to a sugar-containing product, it is acceptable to use the second drop of blood after wiping away the first drop." The study also found that external pressure (or squeezing) of the finger can lead to unreliable readings, as well.
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