What are the diagnostic criteria for Diabetic Ketoacidosis (DKA)?

Diagnosing Diabetic Ketoacidosis (DKA)

DKA is diagnosed when all three criteria are simultaneously present: hyperglycemia (plasma glucose >250 mg/dL), metabolic acidosis (venous pH <7.3 AND serum bicarbonate <18 mEq/L), and elevated blood β-hydroxybutyrate (β-OHB). 1, 2, 3

Core Diagnostic Triad

All three components must be present simultaneously for DKA diagnosis:

• Hyperglycemia: Plasma glucose >250 mg/dL 1, 2, 3
• Metabolic acidosis: Arterial pH <7.3 AND serum bicarbonate <18 mEq/L 1, 2
• Ketosis: Elevated blood ketones (preferably β-hydroxybutyrate) 1, 2, 3

The anion gap should be >10 mEq/L (mild DKA) to >12 mEq/L (moderate/severe DKA). 1

Critical Ketone Measurement: β-Hydroxybutyrate is Mandatory

Measure blood β-hydroxybutyrate (β-OHB) specifically—do NOT rely on nitroprusside-based tests (urine dipsticks or serum tablets). 4, 1, 3

• Nitroprusside methods only detect acetoacetate and acetone, completely missing β-OHB, which is the predominant ketone body in DKA 4, 3
• During treatment, β-OHB converts to acetoacetate, making nitroprusside tests falsely suggest worsening ketosis when the patient is actually improving 1, 2
• Blood β-OHB measurement is the preferred method for both diagnosis and monitoring treatment response 4, 1, 3

Essential Initial Laboratory Workup

When DKA is suspected, immediately obtain:

• Plasma glucose 1, 3
• Venous blood gas (pH and bicarbonate) or arterial blood gas 1, 3
• Serum electrolytes with calculated anion gap 1, 3
• Blood β-hydroxybutyrate (preferred over urine ketones) 1, 3
• Blood urea nitrogen and creatinine 1, 3
• Serum osmolality 1, 3
• Complete blood count with differential 1, 3
• Urinalysis 1, 3
• Electrocardiogram 1, 3

Severity Classification

Once diagnosed, stratify DKA severity based on acidosis degree and mental status:

• Mild DKA: pH 7.25-7.30, bicarbonate 15-18 mEq/L, anion gap >10 mEq/L, alert mental status 1, 3
• Moderate DKA: pH 7.00-7.24, bicarbonate 10 to <15 mEq/L, anion gap >12 mEq/L, alert/drowsy 1, 3
• Severe DKA: pH <7.00, bicarbonate <10 mEq/L, anion gap >12 mEq/L, stupor/coma 1, 3

Critical Pitfall: Euglycemic DKA

Do not dismiss DKA because glucose is <250 mg/dL—euglycemic DKA is increasingly common, especially with SGLT2 inhibitors. 3, 5

• SGLT2 inhibitors significantly increase DKA risk and commonly cause euglycemic DKA (glucose <250 mg/dL with ketoacidosis) 4, 3, 5
• Euglycemic DKA can also occur with continued insulin use, decreased caloric intake, pregnancy, or alcohol consumption 6, 7
• In euglycemic DKA, the diagnosis still requires metabolic acidosis (pH <7.3, bicarbonate <18 mEq/L) and elevated β-OHB, even when glucose is normal or low 2, 5

Differential Diagnosis Considerations

DKA must be distinguished from other causes of high anion gap metabolic acidosis:

• Alcoholic ketoacidosis (AKA): History of alcohol use, glucose typically normal to mildly elevated (rarely >250 mg/dL) or hypoglycemic 1, 3
• Starvation ketosis: Less severe acidosis, lower ketone levels 4
• Lactic acidosis, toxic ingestions: Check lactate, toxicology screen as indicated 1

Resolution Criteria

DKA is resolved when ALL of the following are met:

• Glucose <200 mg/dL 1, 3
• Venous pH >7.3 1, 3
• Serum bicarbonate ≥18 mEq/L 1, 3
• Anion gap ≤12 mEq/L 3

Monitor blood every 2-4 hours during treatment to measure electrolytes, glucose, venous pH, β-OHB, anion gap, BUN/creatinine, and serum osmolality. 3