What can cause a fasting blood sugar of only 63, if nothing has been found to be wrong w/you medical

This is after 12 hours of fasting. I am 35 years old and slightly overweight (need to lose 20 pounds and working on it). There is no history of diabetes on either side of my family. I take Dilantin 100 mg twice daily; Synthroid 0.25 mg daily; and Nexium 40 mg daily. One thing, though: me and my dad's side of the family love to eat candy such as Red Hots and Bit-O-Honey. I am on Weight Watchers, but I work such candy in every single day. Maybe my pancreas produces too much insulin in response to eating sweets? Every other medical problem has been ruled out. Also, recently, I had a random blood sugar done right after I ate pancakes with syrup and orange juice, and my blood sugar was only in the lower 90s.

I don't understand the concern unless your doctor is concerned. Usually there is no concern over a fasting blood sugar unless it is below 40 mg/dL...and you are quite a bit higher than 40 mg/dL. While most labs consider a normal fasting blood sugar to be 70 to 100 mg/dL, a low result often isn't an issue unless it drops below 40 mg/DL.

As to what can cause a low fasting blood sugar:

hypothyroidism

malnutrition

diabetic medication

liver disease

kidney failure

pituitary gland tumor

Addison's disease