An example might be a physician working in an emergency department who receives an unconscious patient wearing a medical identification tag saying DIABETIC.

[4] People with type 1 diabetes mellitus who must take insulin in full replacement doses are most vulnerable to episodes of hypoglycemia (low blood glucose levels).

[6] If it progresses and worsens without treatment it can eventually cause unconsciousness, from a combination of a very high blood sugar level, dehydration and shock, and exhaustion.

Nonketotic hyperosmolar coma usually develops more insidiously than diabetic ketoacidosis because the principal symptom is lethargy progressing to obtundation, rather than vomiting and an obvious illness.

The diagnosis is usually discovered when a chemistry screen performed because of obtundation reveals an extremely high blood sugar level (often above 1800 mg/dl (100 mM)) and dehydration.

Diabetic coma was a more significant diagnostic problem before the late 1970s, when glucose meters and rapid blood chemistry analyzers were not available in all hospitals.

In modern medical practice, it rarely takes more than a few questions, a quick look, and a glucose meter to determine the cause of unconsciousness in a patient with diabetes.

Other conditions that can cause unconsciousness in a person with diabetes are stroke, uremic encephalopathy, alcohol, drug overdose, head injury, or seizure.