Acetaminophen Can Affect Meter and CGM Readings

There’s been evidence as far back as 2009 that acetaminophen can cause inaccurate blood sugar readings with meters. Now, a more recent study suggests that the common pain reliever also might interfere with continuous glucose monitor (CGM) readings, as well.

In July 2009, The Journal of Diabetes Science and Technology published a paper discussing sources of meter errors in measurement of blood glucose levels, including patient use of acetaminophen. Acetaminophen is a mild painkiller and fever reducer that people use as an alternative to aspirin; although it’s been hard for scientists to pin down exactly how acetaminophen works, the drug is believed to moderate the body’s production of prostaglandins, a hormone-like lipid which, among other things, helps regulate sensitivity to pain. Researchers in the 2009 study documented how acetaminophen use seemed to cause errors in blood glucose readings with meters. The paper has found no chemical or metabolic link between acetaminophen and the body’s production of, or sensitivity to, glucose or insulin. The researchers did say older meters were more prone to these erroneous readings than newer meters, but that such fluctuations can be possible with all meters they researched.

Now, a similar inaccuracy has been documented in connection with CGM use. In 2015, clinical investigators published a paper in Diabetes Care describing meter and monitor variations for a group of acetaminophen-using patients who tested both with meters and CGMs. The study, led by Dr. David M. Maahs of the University of Colorado Barbara Davis Center for Childhood Diabetes, was a stress test to predict the reliability of investigational closed-loop artificial pancreas systems relying on CGMs. Study participants took 1,000 milligrams of acetaminophen at breakfast and tested their levels at seven intervals within eight hours using Dexcom G4 monitors and a variety of blood drop test strip meters. Researchers saw the same elevated glucose reading phenomenon as had been found with meters. In some cases CGM variances were recorded of up to 100 mg/dl over meter testing.

Blood drop test strip meters read the electrical current generated by the reaction of blood glucose to a glucose oxidase enzyme impregnated in the test strip. CGM sensors read the electrical current generated by the reaction of blood glucose and glucose oxidase loaded in the sensor tip cannula assembly. It’s believed that one’s own body chemistry can affect the range of inaccuracy exhibited in CGM results, as many CGM users report no elevated blood glucose readings after taking acetaminophen. Also, some CGM users who regularly take acetaminophen have reported that they need to replace their sensor tips more frequently than manufacturer recommendations.

It’s important to identify if this phenomenon is happening regularly in your diabetes self-care, as erroneous readings can lead to dosing more insulin than needed. If you regularly take acetaminophen, it might be important to document whether your blood sugar readings after taking acetaminophen seem incongruous with other readings. As always, consult with your doctor before making any changes in your diabetes self-care or before discontinuing use of a prescribed or doctor-recommended over-the-counter medication.