What are the diagnostic criteria for diabetic ketoacidosis (DKA) in adults?

Diagnostic Criteria for Diabetic Ketoacidosis (DKA) in Adults

According to the American Diabetes Association, the diagnosis of DKA requires all three of the following criteria: blood glucose >250 mg/dL, arterial pH <7.3 or serum bicarbonate <15 mEq/L, and moderate ketonemia or ketonuria. 1

Diagnostic Triad

The three essential components for diagnosing DKA are:

1. Hyperglycemia:

   • Blood glucose >250 mg/dL
   • Note: Euglycemic DKA (glucose <250 mg/dL) can occur, particularly in pregnancy or with SGLT2 inhibitor use 2, 3

2. Metabolic Acidosis:

   • Arterial pH <7.3
   • Serum bicarbonate <15 mEq/L
   • Elevated anion gap >10 mEq/L

3. Ketosis:

   • Elevated serum ketones (preferred method)
   • Or positive urine ketones

Severity Classification

DKA severity can be classified based on the following parameters 1:

Parameter	Mild	Moderate	Severe
Arterial pH	7.25-7.30	7.00-7.24	<7.00
Bicarbonate (mEq/L)	15-18	10-14	<10
Mental Status	Alert	Alert/drowsy	Stupor/coma

Clinical Presentation

Common symptoms and signs include:

• Polyuria and polydipsia (98%)
• Weight loss (81%)
• Fatigue (62%)
• Dyspnea (57%)
• Vomiting (46%)
• Abdominal pain (32%)
• Polyphagia (23%)
• Signs of dehydration
• Kussmaul respirations (deep, rapid breathing)
• Fruity breath odor (acetone)
• Altered mental status (ranging from alert to coma) 4, 2

Laboratory Evaluation

Essential laboratory tests for diagnosis and management:

• Serum glucose
• Arterial or venous blood gas (pH)
• Serum bicarbonate
• Serum ketones (beta-hydroxybutyrate preferred)
• Electrolytes and calculation of anion gap
• Complete blood count
• Blood urea nitrogen and creatinine
• Urinalysis for ketones 1, 2

Special Considerations

1. Euglycemic DKA:

   • Defined as DKA with blood glucose <250 mg/dL
   • More common with SGLT2 inhibitor use, pregnancy, reduced carbohydrate intake, alcohol use, or chronic liver disease
   • Requires high clinical suspicion as hyperglycemia may be absent 2, 3

2. Pregnancy:

   • Up to 2% of pregnancies with pregestational diabetes may be complicated by DKA
   • Pregnant patients may present with euglycemic DKA
   • Requires immediate attention due to risk of feto-maternal harm 1

Resolution Criteria

DKA is considered resolved when:

• Glucose <200 mg/dL
• Serum bicarbonate ≥18 mEq/L
• Venous pH >7.3 1

Common Pitfalls to Avoid

1. Missing euglycemic DKA: Don't rule out DKA solely based on glucose <250 mg/dL, especially in patients on SGLT2 inhibitors or pregnant women.

2. Inadequate monitoring: Once diagnosed, hourly monitoring should include vital signs, neurological status, blood glucose, and fluid input/output, with electrolytes, BUN, creatinine, and venous pH monitored every 2-4 hours 1.

3. Failure to identify precipitating factors: Always search for and treat underlying causes such as infection, missed insulin doses, or new-onset diabetes.

4. Overlooking DKA in type 2 diabetes: About one-third of all DKA cases occur in persons without a prior history of diabetes mellitus 4.

By following a structured diagnostic approach and prompt management, the mortality rate from DKA can be significantly reduced from the historical 2-5% 1.