Japanese researchers are warning diabetics of the risk of “pseudohypergylcemia” when testing blood sugar after eating or handling fruit. A study published in the journal Diabetes Care demonstrated how fruit sugars can stay on the hands even after the fingers are swabbed with alcohol, causing an artificially high blood glucose test reading.
Researchers from the Juntendo University Graduate School of Medicine in Tokyo measured the blood sugar levels of ten non-diabetic volunteers, using a standard glucose monitor to test blood samples taken from a fingertip. They then asked the volunteers to peel oranges, grapes and kiwi fruit.
After the volunteers peeled the fruit, the researchers measured their blood glucose levels three more times – before they washed their hands, after they swabbed their hands with alcohol wipes, and after they washed their hands under running water.
Blood glucose levels taken before the volunteers handled the fruit were normal (an average 90 milligrams per deciliter (90 mg/dl). Glucose test results after they handled the fruit and before they cleaned their hands showed high blood sugar levels – around 360 mg/dl after peeling a grape, 180 mg/dl after peeling a kiwi, and 170 mg/dl after peeling an orange.
Even after they swabbed their hands with alcohol (the recommended practice for a diabetic before testing blood sugar), their blood sugar readings were higher than normal. Surprisingly, the volunteers were still receiving inaccurate blood sugar readings after swabbing five times. It was only after washing their hands under running water that their blood glucose readings returned to normal.
Diabetics rely on accurate blood glucose test results to determine how much diabetes medication to take. A diabetic who handled or ate fruit before conducting their blood sugar test could get an incorrect reading and give themselves an unneeded insulin injection, resulting in low blood sugar.
The take away message for diabetics – don’t rely on alcohol swabs alone to clean your hands, and always wash them with soap and water before testing blood sugar. In the words of the study authors, “To avoid overestimation of blood glucose using portable monitors, their hands should be washed before monitoring capillary blood glucose, especially after fruit has been handled.”