Never used it, always stuck to a pumice stone when needed. As a Diabetic you have to be very careful with your feet. Take a look at this article about the ped egg from a Podiatrist.
An extract:
With all jokes aside, the Ped Egg can be very dangerous for people with diabetes, peripheral vascular disease or any other disease that compromise the healing process or the immune system. Sometimes it only takes a tiny cut for some to get a devastating infection. Any product that has the potential of cutting the skin should be used with severe caution or not at all.