Ask The Expert
Monitoring

Many people have been under the impression that they should wash their hands prior to testing to prevent infection. Although it is always wise to practice good hygiene, it is extremely rare and unlikely to develop an infection at the lancing site. In addition, just as you asked, there is the possibility of getting a false reading if there is something on the fingers (or on alternative sites). Here are points to keep in mind:

• Alcohol left on the skin (if it didn't dry) could dilute the sample and give a falsely low reading. In addition, alcohol has been reported to cause dry skin. The cooling or vasoconstrictive effect of alcohol may lead to less blood produced from the test site.
• Also, water left on the skin can dilute the sample and give a falsely low reading.
• Any sugar on the skin may cause a falsely high glucose reading. In fact, there are many situations involving people who neglected to wash the site after eating something sweet, such as a cookie, and their glucose results were falsely elevated by over 100 mg/dl.
• Note that we do not recommend cleaning the test site with alcohol because our studies suggest that alcohol wipes may not adequately clean the test site in some instances, for example, if the test site is contaminated with carbohydrate foods or certain body lotions.

There is no official list of lotions, etc. that could affect the glucose results, especially since good hygiene practices would include using a clean site regardless.

Conclusion: We recommend cleaning the test site with soap and warm water, which is effective for removing sugary substances and other contaminants. The warm water also enhances blood flow, making it easier to get a blood drop.