27-03: Diabetic Ketoacidosis

ESSENTIALS OF DIAGNOSIS

GENERAL CONSIDERATIONS

Diabetic ketoacidosis (DKA) is a disorder primarily of type 1 diabetes but can occur in patients with type 2 diabetes who have severe illness, such as sepsis or trauma. DKA may be the initial manifestation of type 1 diabetes or may result from increased insulin requirements in patients with type 1 diabetes during the course of infection, trauma, MI, or surgery. It is a life-threatening medical emergency. The National Data Group reports an annual incidence of five to eight episodes of DKA per 1000 persons with diabetes. DKA is one of the more common serious complications of insulin pump therapy, occurring in approximately 1 per 80 patient-months of treatment. Many patients who monitor capillary blood glucose regularly ignore urine ketone measurements, which signals the possibility of insulin leakage or pump failure before serious illness develops. Poor compliance, either for psychological reasons or because of inadequate education, is the most common cause of recurrent DKA.

CLINICAL FINDINGS

A. Symptoms and Signs

The appearance of DKA is usually preceded by a day or more of polyuria and polydipsia associated with marked fatigue, nausea, and vomiting.

If untreated, mental stupor ensues that can progress to coma. Drowsiness is fairly common, but frank coma only occurs in about 10% of patients. On physical examination, evidence of dehydration in a stuporous patient with rapid deep breathing and a “fruity” breath odor of acetone strongly suggests the diagnosis. Hypotension with tachycardia indicates profound fluid and electrolyte depletion, and mild hypothermia is usually present. Abdominal pain and even tenderness may be present in the absence of abdominal disease. Conversely, cholecystitis or pancreatitis may occur with minimal symptoms and signs.

B. Laboratory Findings

Typically, the patient with moderately severe DKA has a plasma glucose of 350–900 mg/dL (19.4–50 mmol/L), serum ketones at a dilution of 1:8 or greater or beta-hydroxybutyrate more than 4 nmol/L, hyperkalemia (serum potassium level of 5–8 mEq/L), mild hyponatremia (serum sodium of approximately 130 mEq/L), hyperphosphatemia (serum phosphate level of 6–7 mg/dL [1.9–2.3 mmol/L]), and elevated BUN and serum creatinine levels (Table 27–10). Acidosis may be severe (pH ranging from 6.9 to 7.2 and serum bicarbonate ranging from 5 mEq/L to 15 mEq/L); PCO₂ is low (15–20 mm Hg) related to compensatory hyperventilation. Fluid depletion is marked, typically about 100 mL/kg. Lactate levels are usually elevated and higher than 2 mmol/L in more than 50 % of the patients. The hyperlactatemia is not due to hypoxia or sepsis and reflects metabolic fuel use in the insulin deficient state. Higher glucose levels and lower pH levels are associated with higher lactate levels. ...