I have a little bit of knowledge of how blood glucose monitors work, and while I recommend the devices for personal use on a regular basis, always caution people of the variability involved. This article provides certain insights that might come in handy as well.
If you have someone who is a diabetic, and/or regularly monitors their blood sugar levels, consider showing them the article (click on title for the article).
If someone you know is a diabetic and is not currently using any form of glucose monitoring, please do recommend atleast one of the various meters available on the market. At the least, they provide a guidance and comfort in times of need!