Topical iodine can cause overestimation of blood glucose

(HealthDay)—Use of topical iodine can cause overestimation of blood glucose (BG) readings, according to a case report published online Aug. 8 in the Journal of Clinical Pharmacy and Therapeutics.

A.M. Lipshutz, Pharm.D., from Mount Carmel West Hospital in Columbus, Ohio, and Emily M. Hawes, Pharm.D., from the University of North Carolina in Chapel Hill, present a case of a clinically relevant probable drug-device interaction between topical iodine and a point-of-care glucometer in a 28-year-old pregnant woman of Chinese descent. On diagnosis of gestational diabetes, the woman was instructed to begin self-monitored BG testing four times daily. She felt the readings were inaccurate, varying from 107 to 160 mg/dL within a five- to 10-minute period. At a clinic visit with a pharmacist, the patient's technique was shown to be appropriate.

On thorough interview of the patient it was discovered that she had been using 10 percent povidone-iodine solution administered to the testing site before testing. The patient was asked to wash her hands with soap and water before testing, resulting in more consistent readings on two point-of-care devices. Following appropriate handwashing techniques, there were no further aberrant BG readings. After discontinuing iodine, all readings remained below her goal throughout pregnancy.

"In patients [who] have aberrant or variable BG readings, providers should investigate for improper testing technique," the authors write.