A diabetic coma is not unlike other types of coma in the fact that there is unconsciousness, and there can be two reasons for the diabetic coma. The Nonketotic hyperosmolar coma and the advanced diabetic ketoacidosis coma are the two types of diabetic comas, along with the Hypoglycemic coma that is also a danger.

Diabetic ketoacidosis comas occur when the diabetic patient has the condition diabetic ketoacidosis and it becomes worse to a point where there is a combination of severe hypoglycemia, dehydration and shock, coupled with exhaustion can lead to coma. The coma stage can begin after about 36 hours of the advanced diabetic ketoacidosis in which there is vomiting and hyperventilation.

The person with diabetes in the middle stages of this condition can appear flushed, breath rapidly and deeply, and there can be signs of visible dehydration.

Nonketiotic hyperosmolar coma has different symptoms; this type of coma will have the main symptom of lethargy. This is a coma that usually affects type II diabetics or people with steroid diabetes. They may have an impaired ability to recognize thirst and often become dehydrated due to this condition. It is also not an uncommon type of coma that elderly diabetics are affected by.