Hydroxyurea interferes with CGM reading in type 1 diabetes patient: Case Report

In subsequent testing with the patient wearing both the Dexcom G6 and a different CGM, the Abbott FreeStyle Libre, for 3 days, glucose readings were similar until the patient took hydroxyurea in the fasting state, at which point they diverged. For example, at one point the Dexcom read 254 mg/dL while the Libre showed 128 mg/dL. At another, the readings were 194 mg/dL versus 89 mg/dL, respectively. The Dexcom glucose readings, but not the Libre's, remained high for 6-10 hours following hydroxyurea administration.

"Our case demonstrated for the first time that hydroxyurea is an interferent in a commonly used CGM system, and providers must be aware that these CGM data must be disregarded for several hours after each hydroxyurea administration," wrote the authors. "This medication-induced interference with CGM and by extension hybrid closed-loop insulin delivery is fortunately rare, and these minor limitations pale in comparison with the wide-ranging, unprecedented, and revolutionary benefits that these technologies have afforded to people living with diabetes."

The case report that led to the revision of the device's label in early 2020 was reported by Emily D. Szmuilowicz and Grazia Aleppo from the Division of Endocrinology, Metabolism and Molecular Medicine at the Northwestern University Feinberg School of Medicine, Chicago, Illinois, and colleagues.

Reference:

"Interferent Effect of Hydroxyurea on Continuous Glucose Monitoring," is published in the journal Diabetes Care.

DOI: https://care.diabetesjournals.org/content/44/5/e89