People with type one diabetes mellitus who must take insulin in full replacement doses are most vulnerable to episodes of hypoglycemia. It is usually mild enough to reverse by eating or drinking carbohydrates, but blood glucose occasionally can fall fast enough and low enough to produce unconsciousness before hypoglycemia can be recognized and reversed. Hypoglycemia can be severe enough to cause unconsciousness during sleep. Predisposing factors can include eating less than usual, prolonged exercise earlier in the day, and heavy drinking. Some people with diabetes can lose their ability to recognize the symptoms of early hypoglycemia.
Unconsciousness due to hypoglycemia can occur within 20 minutes to an hour after early symptoms and is not usually preceded by other illness or symptoms. Twitching or convulsions may occur. A person unconscious from hypoglycemia is usually pale, has a rapid heartbeat, and is soaked in sweat: all signs of the adrenaline response to hypoglycemia. The individual is not usually dehydrated and breathing is normal or shallow. A meter or laboratory glucose measurement at the time of discovery is usually low, but not always severely, and in some cases may have already risen from the nadir that triggered the unconsciousness. Unconsciousness due to hypoglycemia is treated by raising the blood glucose with intravenous glucose or injected glucagon.