idiopathic neuropathy and sugar, not a diabetic

I get neuropathy when I eat. Most thing cause some but sweets cause my feet to go numb, burn and pin and needles. I have been tested many time for diabeties and they say I am not even close. Could this be vasculitus or some RA disease causing the issue. I feelmthe best innthe mornings with little or now neuropathy. As the day goes on and depending on my diet i get inflamed. I do have a bulging disc in my back pressing on nerves but why the sugar would make that so much worse. My Dr is stumped and have no other options for me. I would like to monitor my sugar level continously for a few weeks to see how high I am getting. Can it be insulin intolerance?