Obsessive Nail and cudicle picking

I have a family member who, starting about 10-15 years ago, had one particular fingernail that he would pick until it was literally gone. Now, in the last 6-12 months, he has begun to go from one nail to the next. He picks it until it is completely gone and then moves on to the next one. You can tell him to stop and he will for about 5-10 second and then he goes right back to doing it again. He seems to not even realize that he's doing it as when you call him out on it he'll say he's not doing anything. Now here's the thing: 1.) he evidently feels no pain (as who could continue to do that if it were painful) 2.) his fingers do not bleed and 3.) he's a diabetic (which we've warned him over and over that he MUST stop doing this) but he just can't. He can't seem to control himself. His mother believes it is nerves. Is there a medical term for this type of behavior?

Hi im Marcus (26), im not one for nails but i pick my cuticles and the skin around the nail of my thumbs all day long!! Its getting to the point now where i need to sort this out. On a daily basis i will seek for dry skin and pick and pull until i get it off, even using my preferred weapon of choice the drawing pin to help me. I moisturise on a daily basis but never allow my thumbs/fingers to heal - even when they show signs of healing im reaching for the pin to break and lever the skin out to tear it away. Im not particularly stressed and all in my life is balanced and well both physically and mentally.
This is the interesting thing about me - when i pick the skin on my thumb and it is rough and sharp, i like to rub it on the corner and underneath my mouth (because it is sharp) and makes for a good scratch. I dont want to explore any form of medication - rather seek the route cause perhaps through hypnosis/meditation/discussion etc . . . HAS anybody tried this and found it has helped? I thought about going to the doctors, but my experience in the UK is not the best, i'd imaging they would tell me to put some cream on and be on my way.