Glucometer Errors

Study shows venous blood tests artificially high on capillary glucometers.

Did you know that it matters where you get the blood sample from when you’re using a glucometer? If you did, congratulations. You understand more than I did about glucometers before I read this study that showed venous blood tests as much as 17.42 mg/Dl higher on capillary glucometers than capillary blood.

Why do you care? If your agency is using standard, over-the-counter capillary glucometers, these are specifically calibrated to give accurate readings on capillary blood. The kind of blood your finger oozes when you poke it with a lancet. Not the direct venous blood that you might get off your IV needle or directly from the end of the IV catheter.

Does this mean that you should stop using the IV site, or needle, or little drops of blood on your bench seat to test the patients glucose level? Not necessarily. Venous blood will still give you an accurate ballpark estimate of the patients glucose level. Just be aware that if you’re looking for a dead-on accurate blood glucose level on your diabetic or altered mentation patient, you need to do a finger stick. And know that a venous blood sample reading will most likely be an artificially high number.

Now you know.