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

Diagnostic Criteria for Diabetic Ketoacidosis (DKA)

DKA is diagnosed when all three criteria are simultaneously present: hyperglycemia (plasma glucose >250 mg/dL), metabolic acidosis (arterial pH <7.3 AND serum bicarbonate <18 mEq/L), and positive ketones in blood or urine. 1

Core Diagnostic Triad

The diagnosis requires meeting all three components simultaneously: 1, 2

• Hyperglycemia: Plasma glucose >250 mg/dL (though euglycemic DKA with glucose <250 mg/dL can occur, particularly with SGLT2 inhibitor use) 1, 2
• Metabolic acidosis: Arterial pH <7.3 AND serum bicarbonate <18 mEq/L 1, 2
• Ketosis: Positive serum or urine ketones 1, 2
• Anion gap: Elevated >10-12 mEq/L 1, 2

Preferred Ketone Measurement Method

Blood β-hydroxybutyrate (βOHB) measurement is the preferred diagnostic method rather than nitroprusside-based tests. 1, 2 This is critical because:

• βOHB is the predominant ketone body in DKA 1, 2
• Nitroprusside methods (urine dipsticks, serum tablets) only detect acetoacetate and acetone, NOT βOHB 1
• During treatment, βOHB converts to acetoacetate, making nitroprusside tests falsely suggest worsening ketosis when the patient is actually improving 1, 2

Severity Stratification

DKA severity is classified based on degree of acidosis and mental status: 1

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

Essential Initial Laboratory Workup

When DKA is suspected, obtain: 1, 2

• Plasma glucose 1, 2
• Arterial blood gas (pH, bicarbonate) or venous pH 1, 2
• Serum electrolytes with calculated anion gap 1, 2
• Blood urea nitrogen/creatinine 1, 2
• Serum βOHB (preferred) or serum/urine ketones 1, 2
• Serum osmolality 1
• Complete blood count with differential 1, 2
• Urinalysis 1, 2
• Electrocardiogram 1, 2
• Hemoglobin A1C 3

Additional tests to consider based on clinical presentation include amylase, lipase, hepatic transaminases, troponin, creatine kinase, blood and urine cultures, and chest radiography. 3

Critical Pitfall: Euglycemic DKA

SGLT2 inhibitors significantly increase DKA risk and commonly cause euglycemic DKA (glucose <250 mg/dL with ketoacidosis). 1, 2 This requires:

• Metabolic acidosis (pH <7.3, bicarbonate <18 mEq/L) 1
• Elevated β-OHB 1
• Glucose may be <250 mg/dL 1, 2

Other causes of euglycemic DKA include pregnancy, reduced food intake, alcohol use, and liver failure. 2

Critical Pitfall: Diabetic Ketoalkalosis

DKA can present with pH >7.4 (diabetic ketoalkalosis) due to concurrent metabolic alkalosis or respiratory alkalosis, yet still require full DKA treatment. 4 In one study:

• 23.3% of DKA cases presented with pH >7.4 4
• 34% of these alkalemic presentations had severe ketoacidosis (βOHB ≥3 mmol/L) 4
• All cases had increased anion gap metabolic acidosis despite alkalemic pH 4

This means you cannot exclude DKA based on normal or elevated pH alone—check βOHB and anion gap. 4

Differential Diagnosis

Distinguish DKA from other causes of high anion gap metabolic acidosis: 1, 2

• Alcoholic ketoacidosis: Clinical history of alcohol use, glucose typically normal to mildly elevated (rarely >250 mg/dL) or hypoglycemic 1, 2
• Starvation ketosis: Less severe acidosis and lower ketone levels 1
• Lactic acidosis 2
• Toxic ingestions: Salicylates, methanol, ethylene glycol 2

Resolution Criteria

DKA is considered resolved when: 1

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