Every single time a number in the 300’s pops up on our blood glucose meter, I instruct Q to go wash her hands again and we do another test.
Because one time when Q was low I gave her some Skittles. Fifteen minutes later she was in the 300’s! I thought that surely a 10 gram carb serving of Skittles wouldn’t shoot her up more than 200 points! After a hand wash and another BG check, we realized she was nicely in range. That sugar on her finger caused a false high reading. Could you imagine if I gave a correction based on that high number?
Now each time the school calls with a high reading my first question is: Did you have her wash her hands and check her again?
When I mentioned that we only go through a box or two of alcohol swabs a year since switching to an insulin pump (read about the alcohol swab recall), I had several parents ask why we don’t wipe Q’s finger with an alcohol swab before a BG check.
We did this in the beginning, but quite quickly the CDE told us to switch to good old soap and water. Alcohol dries the fingertips and can make finger pricking more painful.
A recent study published in the American Diabetes Association’s Diabetes Care journal verifies that not only can you get false high readings from sugary residues on fingers, but also that soap and water is best.
Though I have to wonder how many hundreds of thousands, if not millions, of dollars were spent to find this out!
Here is the abstract:
OBJECTIVE To examine whether hand contamination with fruit results in a false blood glucose (BG) reading using capillary fingertip blood sample.
RESEARCH DESIGN AND METHODS The study subjects were healthy volunteers with normal glucose tolerance test. Capillary BG samples were collected from the fingertip after peeling orange, grape, or kiwi fruit, followed by no action, washing hands with tap water, or rubbing the fingertip with an alcohol swab, then analyzed with glucose monitors.
RESULTS The BG levels measured after peeling any of the fruits, followed by washing hands, were similar to the control subjects (no fruit handling), but the levels after fruit peeling, followed by no washing, were abnormally and significantly high, even when the fingertip was cleaned once or five times with an alcohol swab before blood sampling.
CONCLUSIONS To avoid overestimation of blood glucose using portable monitors, the hands should be washed before monitoring capillary BG, especially after fruit has been handled.