**7. Acute metabolic complications**

Patients with diabetes are susceptible to four acute metabolic complications: hypoglycemia, ketoacidosis, hyperosmolar and lactic acidosis. All of them can result in coma. The two first are complications of IDDM, while the other two are usually developed in the setting of NIDDM. These clinical situations must be considered completely different from severe disorders that occur not related to DM *per se* such as stroke, acute heart failure, hepatic dysfunction, in others words: *coma* in *diabetic patients* is completely different for *diabetic coma*.

Unfortunately, a lot of patients developed coma situations despite the treatments available, generally caused by incorrect dose, or medication missed dose. This is the relevant point to consider other possibilities, and the way is clinical trial.

*Diabetic ketoacidosis*. It is often caused by cessation of insulin administration but it may result from physical (infection, surgery, traumatism) or emotional stress despite continued insulin therapy. Several complications can be present in diabetic ketoacidosis: erosive gastritis or acute gastric dilatation manifested by pain, vomiting of blood, or weight lost, cerebral edema with or without neurological signs or coma, increased potassium serum (cardiac arrest); myocardial infarction, respiratory distress syndrome, or thrombosis events.

*Hyperosmolar coma*. This modality of acute diabetes complication is usually due to NIDDM. It is characterized by a profound dehydration resulting from a sustained hyperglycemic diuresis by situations in which the patient is unable to drink enough water to keep up normal urinary excretion of detritus. This situation commonly occurs in elderly patients often living alone or in a nursing home. They develop stroke or bacterial infection that worsens adequate water intake. Hyperosmolar coma can also be caused by peritoneal dialysis or hemodialysis, the use of osmotic agents such as manitol and urea. Clinically, patients show extreme hyperglycemia, hyperosmolality and central nervous system disorders (seizure activity, transient stroke, hemiplegia or clouded sensorium and coma). Pneumonia, gram-negative sepsis or others infections are also very common. Bleeding probably caused by disseminated intravascular coagulation, acute pancreatitis and widespread thrombosis is usually found at necropsy.

*Lactic acidosis*. It is a serious clinical finding that can occur because of an increase in endogenous lactic acid, the final step of the carbohydrate metabolism. That causes profound effects on the respiratory, cardiac and nervous systems. The blood pH drop suddenly and is accompanied by an increase in respiratory ventilation (Adolph Kussmaul, 1822-1902), depression of cardiac contractility, pulmonary edema and altered central nervous system function manifested with headache, lethargy, stupor, or in such patients even coma. The prognosis is very bad and most of the patients die soon.
