Hi FlyingDutchWoman, the damage could have been done well before the actual diagnoses of diabetes, trouble is with diabetes it isn't always diagnosed until complications do pop up, of course there are other possible causes as well, like vitamin defiencies etc, which some can be eliminated by simple blood tests.
If it is caused by the elavated blood sugars the good news is that with tight sugar control the nerves can heal over time.

Brian