Numbness in toes and soles of feet

I started feeling that my socks were folded under my foot,or there was something in my shoe about 3 years ago. I then realized it was numbness. Then a year later my toes began to loose feeling. I have no pain and can play tennis and go for long walks. I am 57, a type-2 Diabetic and I am 300 lbs. My DPM says it is not a diabetic problem. My MD has'nt a clue. I have had back promlems all of my life, due to a slight malgrowth in my lower spine. Could there be a connection? Any suggestions as to where I'm headed with this? If you have experienced the same symptoms, Please contact me. How can I stop the spread of this neuropathy?