what causes low body temp.?

Answer 1

There really are no significant diseases which lead to hypothermia. The most common cause of hypothermia is exposure to cold. This is usually a secondary event from some other entity. Mental retardation, alcohol or drug intoxication, dementia, injury that prevents a patient from getting inside: ie. hip injuries, stroke.

Metabolically, hypoglycemia (which decreases metabolism by depleting metabolic fuel availability) can lead to hypothermia. This is almost always secondary to inappropriate insulin use in a diabetic.

I hoped this helped some, this can be somewhat complicated without a good understanding of physiology.