When can diabetic ketoacidosis (DKA) be diagnosed?

Diagnostic Criteria for Diabetic Ketoacidosis (DKA)

Diabetic ketoacidosis (DKA) can be diagnosed when a patient presents with the triad of hyperglycemia (blood glucose >250 mg/dL), metabolic acidosis (pH <7.3, serum bicarbonate <18 mEq/L), and elevated ketones in blood or urine. 1

Essential Diagnostic Criteria

The formal diagnostic criteria for DKA include:

• Blood glucose: Typically >250 mg/dL, though euglycemic DKA (glucose <250 mg/dL) can occur, especially with SGLT2 inhibitor use 1, 2
• Arterial pH: <7.3 (severity-based classification)
  • Mild: 7.25-7.30
  • Moderate: 7.00-7.24
  • Severe: <7.00 1
• Serum bicarbonate: <18 mEq/L (severity-based)
  • Mild: 15-18 mEq/L
  • Moderate: 10 to <15 mEq/L
  • Severe: <10 mEq/L 1
• Ketones: Positive in serum and urine 1
• Anion gap: >10-12 mEq/L (elevated) 1
• Mental status: Can range from alert to coma depending on severity 1

Laboratory Evaluation

When DKA is suspected, the following tests should be performed:

• Essential tests:

  • Plasma glucose
  • Blood urea nitrogen/creatinine
  • Serum ketones (preferably β-hydroxybutyrate)
  • Electrolytes with calculated anion gap
  • Arterial blood gases
  • Urinalysis and urine ketones
  • Complete blood count with differential 1

• β-hydroxybutyrate measurement:

  • Specific measurement of β-hydroxybutyrate in blood is preferred for diagnosis and monitoring of DKA 1
  • Nitroprusside-based ketone tests (urine or blood) do not measure β-hydroxybutyrate, the predominant ketone in DKA 1

Clinical Presentation

DKA typically presents with:

• Symptoms: Polyuria, polydipsia, polyphagia, weight loss, vomiting, abdominal pain, dehydration, weakness, and altered mental status 1
• Physical findings: Poor skin turgor, Kussmaul respirations, tachycardia, hypotension, and potentially altered mental status 1
• Time course: DKA typically evolves rapidly (usually <24 hours) compared to HHS, which develops over days to weeks 1

Special Considerations

• Euglycemic DKA: Can occur with:

  • SGLT2 inhibitor use
  • Pregnancy
  • Reduced food intake
  • Alcohol use
  • Liver failure 1, 2

• Diabetic ketoalkalosis: A variant where patients have ketosis and increased anion gap but pH >7.3 or even >7.4 due to mixed acid-base disorders (occurs in approximately 23% of cases) 3

• Differential diagnosis:

  • Alcoholic ketoacidosis: Distinguished by clinical history and glucose levels rarely >250 mg/dL
  • Starvation ketosis: Serum bicarbonate usually not <18 mEq/L
  • Other causes of high anion gap metabolic acidosis: Lactic acidosis, salicylate/methanol/ethylene glycol ingestion 1

Precipitating Factors

Common precipitating factors for DKA include:

• Infection (most common)
• New-onset type 1 diabetes
• Insulin omission or inadequate insulin
• Cerebrovascular accident
• Myocardial infarction
• Trauma
• Drugs (corticosteroids, thiazides, sympathomimetic agents)
• Alcohol abuse
• Pancreatitis 1

Monitoring During Treatment

• β-hydroxybutyrate levels should be used to monitor treatment response rather than nitroprusside-based ketone tests 1
• Resolution of acidosis or reduction in blood β-hydroxybutyrate is the marker for successful treatment 1

Remember that DKA is a medical emergency with significant morbidity and mortality if not promptly diagnosed and treated. Early recognition of the diagnostic criteria and immediate intervention are essential for positive outcomes.