I have heard some people say it has helped them, but there is little in the way of scientific evidence to demonstrate that benefit, and they are relatively expensive for what they are.
You could get the same benefit by wiggling your toes and clenching and unclenching your calf muscles, or even taking some regular exercise - all of which are bit less expensive ;)
There are some tips at this link talking about measures to warm up cold feet that you might feel of interest, ethel.
http://www.diabetesmonitor.com/supplies/foot-care/diabetes-and-cold-feet.htm
If you have tried these, and are still not getting any relief then it might be worth giving the circulation boosters a go :)