Have you had your B12 and Vit D measured?

Also diabetics improve with some attention to magnesium.
Magnesium is lost in the urine in diabetics, so their needs are
greater than others. Avoid supplements composed of OXIDE form as those are not absorbed.

Attention to these 3 critical nutrients can often provide some relief.
The B12 should be 400pg/ml at least...don't accept "normal" which might be below that level. Vit D is also helpful for tingling.
Tingling in the face can signal deranged calcium metabolism and fixing Vit D improves that.

If you are taking a statin drug, consider how toxic they are to nerves. You might have to study the statin information coming out within the last year to see if these drugs provide any benefit for you really, as they destroy your cells on a daily basis.

Lots of new information here:
http://neurotalk.psychcentral.com/thread197080.html
Including a video explaining how cells die from statins, and also
new photos of damaged nerves.
also:
http://neurotalk.psychcentral.com/thread122889.html

If you are on a statin, which most diabetics are, you need good doses of CoQ-10 at least. This may not help with nerve damage per se but it may protect your heart muscle some.
300mg a day of the older form gel cap.
100mg a day of the new solubilized types like Qunol.