This is a different physician and i have a bit of input to share with you that hopefully will be helpful..
I would agree with you that you want to be able to get accurate home blood pressure readings,,,
There can be different reasons for an error message on these home BP units..
Low batteries or poor positioning are a couple of reasons that this can happen..
If your BP is too high or too low for the machine to read then that may be a reason..
You might try getting BP checked at a store machine such as a pharmacy ( CVS / Walmart, etc..)
You may get a quick nurse visit at most doctor's offices or an urgent care and they could quickly check both a blood sugar or blood pressure reading for you...
Most primary care offices would be happy to check these for you to get a quick answer for you...
Yes, it may be a wise step to have your own glucometer at home and learn to use it.. ( Here again a nurse at your doctor's office would be happy to help..)
What type SYMPTOMS were you having earlier today ?? That may be helpful to clue in as to what may have been going on..
It has been some time since your initial question so I hope that you are feeling better now...
Let me know if you have further questions for me and I too will be happy to get back with you!
I hope that this is helpful for you.
Anthony Bray MD