itch in upper arms

[railgolf]

I have diabeties and have developed a severe itch that comes and gos for days at a time.  The itch occurs only to one arm at a time and occurs to both arms.  I have been seen by a few Dr.s and have not found a cure for this.  I find that placing ice on the area reduces the itch.  I scratch so much that it wakes me up and I tear the skin and bleed.  Also there is no indications on the skin.

Any ideas