Several things may cause numbing in your feet. One cause could be from diabetes. When diabetes is untreated, unrecognized, or undertreated it can cause damage to your nerves. This condition is known as neuropathy.
Another cause could come from circulatory problems in your feet. If you are wearing shoes that are too tight, the circulation, or blood flow, to your feet can be decreased. If you have unknown, untreated, or undertreated high blood pressure, this too can cause circulation problems, which could lead to numbness in your feet.
If you have any type of decreased flow to or from your feet, numbness in your feet may also arise.