Clinically significant hyperglycemic syndromes consist of diabetic ketoacidosis (DKA) and the hyperglycemic hyperosmotic state (HHS), frequently also referred to as hyperosmotic nonketotic syndrome. The American Diabetes Association definitions for these conditions are given in Table 1
. Serum glucose level is usually below 800 mg/dL in DKA, whereas in HHS a glucose level in excess of 1,000 mg/dL is not uncommon. DKA is characterized by a syndrome of hyperglycemia, ketonemia, and an anion gap metabolic acidosis, usually in excess of 20.
The degree of acidosis and magnitude of the increase in anion gap are contingent on the rate of ketoacid production and urinary excretion. Hyperglycemia produces glycosuria and an osmotic diuresis, resulting in extracellular fluid volume depletion, which can be profound and result in hypotension. Many of the symptoms of DKA result in large measure from this: polyuria, polydipsia, tachycardia, and lethargy. The degree of acidosis is the primary determinant of depressed sensorium. In addition, other symptoms such as nausea, vomiting, abdominal pain, and Kussmaul respirations with a characteristic fruity breath may be present.