Is diabetic hairloss reversable?

Not that much: Diabetic hairloss has a lot to do with the decrease blood flow to that area; there are some medications and topical creams which may help some.

Depends on cause!: Depending on the type of diabetes. If it type one or Insulin dependant, it is probably related to autoimmune hair loss. This is where the body attacks itself which leads to diabetes by attaching the pancreas and to hair loss. If that is the case steroids injections in the scalp could help but could raise your blood sugar.