Should you try alternate site testing?
If you're wincing every time you prick your finger to test your blood sugar, alternate site testing may be for you. Alternate site testing involves using a different body part, such as the palm, upper arm, forearm, thigh or calf, to obtain blood for a glucose reading. One major difference of using an alternate site to a fingertip can be less pain; fingertips are full of nerve endings while other body parts are typically less tender.
"Pricking the skin on alternate sites almost always hurts less than checking on the fingertips, which are highly sensitive," said Gary Scheiner, CDE, the owner and manager of Integrated Diabetes Services, a private practice for helping people manage their diabetes properly. "In most cases, a person will not feel anything when pricking the skin on an alternate site, if the procedure is performed correctly."
Alternate site testing: When the fingertip should come first
Although typically less painful, blood from alternate sites may be more likely to give an inaccurate result. This is because the blood from these areas may be combined with interstitial fluid, found under the skin. "This fluid may not have the same exact glucose concentration as the blood," said Scheiner.
Also, changes in blood sugar typically takes several minutes to be seen in the interstitial fluid, "so there can be a bit of lag time. If the blood sugar is rising or falling quickly, it is usually best to obtain a capillary blood sample from a fingertip," he said.
Test results from an alternate site might differ from a fingerstick, according to information from Bayer Diabetes Care. The reasons can include the differences in blood circulation, blood flow rates and the number of small blood vessels available in different body parts, such as an arm or a leg, as compared to what happens in the fingertips.
Other times to stick to fingertip testing are when you have just taken insulin, if you have recently had a meal, or you are in the middle of or just finished a workout. In addition, if you have hypoglycemia unawareness, are sick, are stressed, or if the results of an alternate site test don't match the way you feel (such as giving an abnormally low reading if you feel fine), always test using blood from your fingertip.
And finally, don't make dosing decisions based on alternate site tests.
"Never use alternate site testing to calculate an insulin dose or to calculate a reading on your continuous glucose monitor," said Solveig Halldorsdottir, PhD, the director of scientific affairs for Bayer HealthCare Diabetes Care.
Alternate site testing tips
People with type 2 diabetes who don't use insulin may find alternate site testing easier to incorporate regularly than those on insulin, but anyone can try alternate site testing. "People in some occupations, such as typists, musicians, and others who frequently work with their hands may want to prevent their fingertips from overuse" may also be more interested in trying alternate site testing, added Halldorsdottir.
Scheiner, who has lived with type 1 diabetes for 26 years, said that droplet size can be a factor when squeezing blood from body parts other than the fingers. "For most people, it is difficult to obtain more than 0.5 microliters of blood from an alternate site," he said. "Meters that require more blood aren't the best for performing alternate site testing."
Also, keep in mind the washability of what you're wearing. "Something I've experienced personally is that bloodstains on the clothes are common, particularly when using the forearms for alternate site testing," he added. "Anyone wearing a long-sleeved shirt should keep a tissue over the site for several seconds after applying blood to the test strip -- just to make sure the bleeding has stopped completely."
And finally, make sure you are using the right machine when doing alternate site testing: you'll need a blood glucose meter that is especially designed to work with alternate sites, along with the appropriate test strips.
Interview with Gary Scheiner, CDE, Integrated Diabetes Services