A state of profound unconsciousness in which the patient cannot be roused and reflex movements are absent. Signs include long, deep, sighing respirations, a rapid, weak pulse, and low blood pressure. Usually the result of a STROKE, coma may also be due to high fever, DIABETES MELLITUS, GLOMERULONEPHRITIS, alcohol, EPILEPSY, cerebral TUMOUR, MENINGITIS, injury to the head, overdose of INSULIN, CARBON MONOXIDE poisoning, or poisoning from OPIUM and other NARCOTIC drugs. Though usually of relatively short duration (and terminating in death, unless yielding to treatment) it may occasionally last for months or even years. (See UNCONSCIOUSNESS; GLASGOW COMA SCALE.)