People with diabetes are urged to always wash their hands before testing their blood sugar. But if soap and water are nowhere to be found, using the "second drop" of blood may be OK, a new study suggests.
Many people with diabetes have to test their blood sugar every day, in order to adjust their dose of insulin, plan their next meal and generally manage the disease. They do that by making a small prick on a fingertip, then placing a drop of blood on a test strip that is read by a glucose monitor.
The American Diabetes Association and other groups say that people should thoroughly wash and dry their hands, then test the first drop of blood that comes from the finger.
They do not, however, have advice on what to do when you cannot wash your hands.
For the new study, Dutch researchers had 123 people with diabetes test their blood sugar under various conditions: after thoroughly washing and drying their hands; without handwashing; after handling fruit, which leaves sugar on the fingers; and after washing their fruity fingers.
The participants also tested their blood sugar using varying amounts of pressure to squeeze a drop of blood from the tested finger. (In general, guidelines advise against squeezing the finger too hard to get a blood drop because it may distort blood sugar readings.)
Overall, the study found, clean hands are still key.
Compared with tests of clean hands, 11 percent of study participants had test results that were at least 10 percent off when they tested the first drop of blood from their unwashed hands. The same was true of 4 percent of study participants when they used the second drop of blood.
Based on that, the researchers recommend that people wash and dry their hands before testing, then use the first blood drop. But if they cannot wash up for some reason, it's "acceptable" to use the second drop after wiping away the first.
But what about fruity hands?
In that case -- or whenever hands are visibly dirty -- a good washing is necessary, according to the researchers, led by Johanna Hortensius, a registered nurse at the Isala Clinics Diabetes Center in Zwolle, the Netherlands.
They found that when study participants tested fruit-exposed hands without washing, 88 percent had blood sugar levels that were at least 10 percent off from their clean-hand readings -- at least when using the first drop of blood.
They fared better when using the second drop. But 11 percent still had results that differed substantially from their clean-hand measurements.
The findings are published in the early online edition of the journal Diabetes Care.
As for squeezing the finger, the researchers found that too much pressure did appear to interfere with accurate test results.
Anywhere from 5 to 13 percent of study participants had a significantly different blood sugar result (versus no squeezing), depending on how much pressure they put on the finger.
On average, blood sugar readings were lower when people put pressure on the finger.
The finding, according to the researchers, is in line with advice to avoid firm squeezing of the tested finger.