Before testing, it's recommended to prepare the skin by washing your fingers with warm water and soap, or disinfecting them with an alcohol swab; both methods are acceptable. The American Diabetes Association recommends washing your hands with soap and running water as skin preparation before finger-prick blood glucose testing. However, regardless of the method, it's crucial to remember that the finger must be dry before drawing blood. That is, after washing with warm water and soap, allow your fingers to air dry completely; after disinfecting with alcohol, wait for the alcohol to completely evaporate before pricking your finger with the lancing device to ensure accurate measurement.
It is important to emphasize that iodine-containing disinfectants (such as povidone-iodine or iodine tincture) should not be used to disinfect the skin. In blood glucose monitoring systems using the glucose oxidase principle (including electrode-based and photochemical-based blood glucose meters), the iodine in iodine tincture or povidone-iodine can react with the enzymes in the blood glucose test strip, causing errors. This is because: in electrode-based blood glucose meters, when whole blood is dripped onto the reaction area of the test strip, the glucose in the sample reacts with the chemical substrate (enzyme), generating an electric current. The blood glucose level is calculated by detecting the intensity of this current. Iodine can also react with the enzyme, thus interfering with the current reading and causing inaccurate blood glucose readings. Blood glucose meters based on the photochemical method detect blood glucose levels by measuring the color change of the test strip during the reaction process. Iodine can interfere with the color change through the aforementioned chemical reaction and its own color, thus affecting the accuracy of the blood glucose reading.
