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

The American Diabetes Association requires all three components to be present simultaneously for DKA diagnosis 1, 3:

• Hyperglycemia: Plasma glucose >250 mg/dL 1, 2, 3
• Metabolic acidosis: Venous pH <7.3 AND serum bicarbonate <15-18 mEq/L 1, 2, 3
• Ketosis: Elevated blood ketones, measured as β-hydroxybutyrate 1, 3

The anion gap should be >10-12 mEq/L, reflecting the accumulation of unmeasured ketoacids 1, 4.

Critical Ketone Measurement

Blood β-hydroxybutyrate (β-OHB) is the mandatory test for diagnosing DKA—never rely on urine ketones or nitroprusside-based tests. 1, 3

• Nitroprusside methods (urine dipsticks, serum tablets) only detect acetoacetate and acetone, completely missing β-OHB, which is the predominant ketone body in DKA 1, 3
• During treatment, β-OHB converts to acetoacetate, making nitroprusside tests falsely suggest worsening ketosis when the patient is actually improving 1
• Urine ketones can be falsely negative early in DKA and should never be used for diagnosis 3

Essential Initial Laboratory Workup

When DKA is suspected, immediately obtain 1, 3:

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

Severity Classification

Once DKA is diagnosed, classify severity based on the degree of acidosis and mental status 1, 3:

• Mild DKA: pH 7.25-7.30, bicarbonate 15-18 mEq/L, anion gap >10 mEq/L, alert mental status 1, 2, 3
• Moderate DKA: pH 7.00-7.24, bicarbonate 10-15 mEq/L, anion gap >12 mEq/L, drowsy/lethargic 1, 2, 3
• Severe DKA: pH <7.00, bicarbonate <10 mEq/L, anion gap >12 mEq/L, stuporous or comatose 1, 2, 3

Critical Pitfall: Euglycemic DKA

Never dismiss DKA because glucose is <250 mg/dL—euglycemic DKA is increasingly common, especially with SGLT2 inhibitors. 1, 3, 5

• SGLT2 inhibitors significantly increase DKA risk and commonly cause euglycemic DKA (glucose <250 mg/dL with ketoacidosis) 1, 3, 5
• Euglycemic DKA still requires metabolic acidosis (pH <7.3, bicarbonate <18 mEq/L) and elevated β-OHB for diagnosis 1, 6
• Other causes of euglycemic DKA include recent insulin use with decreased caloric intake, pregnancy, heavy alcohol consumption, and chronic liver disease 6, 7
• Maintain high suspicion for DKA in any patient with metabolic acidosis and ketosis, regardless of glucose level 5, 6

Differential Diagnosis

DKA must be distinguished from other causes of high anion gap metabolic acidosis 1:

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

Resolution Criteria

DKA is considered resolved when ALL of the following are met 1, 3:

• 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

Never stop insulin therapy when glucose normalizes before ketoacidosis resolves—this is a common and dangerous error. 2