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The glucometer is one of the devices that we quickly reach for in the management of our unresponsive patients, diabetics and in the critically ill. Recently, I noticed that our Roche Accu-Check has a big sticker on the case stating that results could be affected by therapies that alter the metabolism of galactose, maltose, and xylose. Since this was a big hole in my fund of knowledge I decided to look up what else affects the accuracy of glucometers.
Now, Dr. Winters already warned used about the inaccuracy of bedside glucometer readings in the critically ill, but what about the patient that is not septic and/or in shock.
Substances/Drugs that have been reported to affect the accuracy of glucometers are:
- Levodopa
- Dopamine
- Mannitol
- Acetaminophen
- Severe lipemia
- Severe unconguted bilirubin
- Elevated Uric Acid
- Maltose (present in immunoglobin products)
- Patient on peritoneal dialysis secondary to Icodextrin
- Ascorbic Acid (Vitamin C)
Anemia also results in higher values, and a capillary blood sample can differ from venous blood by as much as 70mg/dL.
Most errors are more significant when dealing with hypoglycemia.
So the moral of the story is be careful with a bedside glucometer when the reading is low, as the venous blood sample sent to the lab may return even lower. Error on the side of treating the patient with glucose.
References
Fahy BG, Coursin DB. Critical glucose control: the devil is in the details. Mayo Clin Proc. Apr 2008;83(4):394-397.