Will biting your nails cause gum disease and diabetes?

Not in my opinion: No. It may hurt your nails and possibly your teeth but nothing else.

No: Gum ideas ie caused by bacteria present in the mouth together w/ poor home care, lack of good brushing and flossing, genetic predisposition, and local irritants, such as smoking. Diabetes is caused by a problem in your pancreas where you do not produce enough insulin.

See below: Biting your nails can sometimes cause gum recession or clefting. I am not aware of any studies correlating diabetes to nail biting.

No: No, but it can chip and crack your front teeth, or even knock out any fillings that you may have in front teeth, especially on those on the biting surface. Diabetes is related to improperly functioning pancreas.