Back to Ask the Diabetes Team Ask the Diabetes Team

From San Diego, California, USA:

I am an E.R. nurse. We do a few shifts per month at the County Jail. One ward has insulin-dependent diabetics only. We just found out last week that a few of the guys have a trick for making the glucometer read low. I bet this is not new to some, but it was to all of us: a quick swipe of the alcohol on the strip prior to placing the drop of blood on it drops the reading by 60 points. So, the inmate will call on the intercom and say "Nurse, I'm having a reaction, I don't feel well." We go, we check the blood sugar, it reads 36. Well, I was suspicious already because clinical signs did not match the number on the machine! But I could not figure it out! Okay, so to play it on the safe side we'll give them some juice, a sandwich, fruit, etc. One of them "snitched" on the group and told me what the trick was when I refused to become alarmed to a "19" on the machine, and told them as a group I knew they were doing something, although I didn't know how. I didn't give a snack or glucose tab.


  1. Are there any other tricks we should know about?

  2. Is there anything in the literature that does not encourage or discourages the use of alcohol on the finger prior to the finger stick?

  3. Is it necessary to use alcohol on the skin prior to injecting insulin? We've removed the alcohol swabs from the tray.

Any help would be ever so appreciated!


Blood glucose meters are accurate only if they are used properly. Yes, there are a variety of ways to get false readings: another common problem is when not enough blood is used.

The safest approach would be to observe all blood glucose monitoring carefully. I would refer to your policies and procedures about the use of alcohol. Patients at home often wash their hands rather than use alcohol.


Additional comments from Dr. Lebinger:

Whether they use alcohol or soap and water to clean their hands, make sure their fingers are dry. Wet fingers give a false low reading also.


[Editor's comment: As discussed, there are a myriad of ways to fool blood sugar meters. It is also important to know that some tricks that work with one brand of meter might not work as well as with another brand. I would assume that most diabetes nurse educators learn a new one from their patients (or their families), or from letters that are published in diabetes journals, every now and then; I'd suggest you talk to the diabetes nurses at the nearest diabetes program, and learn what else is known about fooling the brand of meter that is used at your facility.

And ask for a change in the policies about using alcohol on the skin, to use soap and water instead of alcohol. Alcohol's unlikely to kill all the germs (especially with a single swipe), may toughen the skin, hurts if the alcohol is still wet when the skin is pierced, and alters the readings of some meters (as you've noticed). WWQ]

Original posting 19 Mar 1998
Posted to Blood Tests and Insulin Injections


  Back to Ask the Diabetes Team Return to the Top of This Page

Last Updated: Tuesday April 06, 2010 15:08:56
This Internet site provides information of a general nature and is designed for educational purposes only. If you have any concerns about your own health or the health of your child, you should always consult with a physician or other health care professional.

This site is published by T-1 Today, Inc. (d/b/a Children with Diabetes), a 501c3 not-for-profit organization, which is responsible for its contents. Our mission is to provide education and support to families living with type 1 diabetes.
By using this site, you agree to our Terms of Use, Legal Notice, and Privacy Policy.
© Children with Diabetes, Inc. 1995-2018. Comments and Feedback.