Both diabetes insipidus and diabetes mellitus can, if incorrectly managed, lead to unconsciousness and even death.

The symptoms of hyperglycemia (too much blood sugar) come on gradually, while those of hypoglycemia (too little blood sugar) can be sudden and dramatic. Diabetics usually carry a card or bracelet warring of their condition, and giving instructions about what to do in emergencies. If the concentration of sugar in the blood drops suddenly, the diabetic becomes faint and appears to be drunk; there is sweating, shallow rapid breathing, and a rapid pulse. Give sugar in any form, unless the person is already unconscious, in which case place him or her in the recovery position (see Unconsciousness) and dial 911.

NB Patients on the new generation of Human Insulins may not show the classic early symptoms of hypoglycemia.