What are the diagnostic criteria and treatment for diabetic ketoacidosis (DKA)?

Diagnostic Criteria for Diabetic Ketoacidosis (DKA)

DKA is diagnosed when blood glucose >250 mg/dL (or prior diabetes history), venous pH <7.3, serum bicarbonate <15 mEq/L, and elevated blood β-hydroxybutyrate are present simultaneously. 1

Core Diagnostic Triad

The diagnosis requires three components present at the same time: 2

• Hyperglycemia: Blood glucose >250 mg/dL 1
• Metabolic acidosis: Venous pH <7.3 AND serum bicarbonate <15 mEq/L 1
• Ketosis: Elevated blood β-hydroxybutyrate (β-OHB) 2

Critical Exception: Euglycemic DKA

Approximately 10% of DKA cases present with glucose <200 mg/dL, termed euglycemic DKA. 3 This occurs with:

• SGLT2 inhibitor use (most common cause) 3, 2
• Pregnancy 3
• Reduced food intake/starvation 3
• Chronic alcohol use 3
• Chronic liver disease 3

Never dismiss DKA because glucose is <250 mg/dL—euglycemic DKA is increasingly common, especially with SGLT2 inhibitors. 2

Severity Classification

DKA severity determines monitoring intensity and prognosis: 1

• Mild: pH 7.25-7.30, bicarbonate 15-18 mEq/L, alert mental status 1
• Moderate: pH 7.00-7.24, bicarbonate 10-15 mEq/L, drowsy/lethargic 1
• Severe: pH <7.00, bicarbonate <10 mEq/L, stuporous/comatose—requires intensive monitoring including possible central venous and arterial pressure monitoring 1

Essential Laboratory Workup

Obtain immediately upon presentation: 1

• Complete metabolic panel (electrolytes, BUN, creatinine) 1
• Venous blood gas (pH, bicarbonate) 1
• Blood β-hydroxybutyrate (β-OHB)—preferred ketone measurement 1, 2
• Complete blood count 1
• Urinalysis 1
• Serum osmolality 2
• Electrocardiogram 2
• Calculate anion gap: [Na⁺] - ([Cl⁻] + [HCO₃⁻]), should be >10-12 mEq/L in DKA 1
• Correct serum sodium for hyperglycemia: [measured Na] + [(glucose - 100)/100] × 1.6 1

Additional Tests When Indicated

• Bacterial cultures (blood, urine, throat) if infection suspected 1
• Amylase, lipase if abdominal pain present 4
• Troponin, creatine kinase if cardiac symptoms 4
• Chest radiography if respiratory symptoms 4
• A1C level 4

Critical Ketone Measurement Pitfall

Never rely on urine ketones or nitroprusside-based tests for diagnosis or monitoring. 1, 2 These methods only measure acetoacetate and acetone, completely missing β-hydroxybutyrate—the predominant and strongest ketoacid in DKA. 1, 2 During treatment, β-OHB converts to acetoacetate, making nitroprusside tests paradoxically appear worse even as the patient improves. 1

Direct blood β-hydroxybutyrate measurement is the gold standard. 1, 3, 2

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Treatment of Diabetic Ketoacidosis

Fluid Resuscitation

Begin aggressive fluid resuscitation with isotonic saline at 15-20 mL/kg/hour immediately to restore circulatory volume and tissue perfusion. 1

• Subsequent fluid choice depends on hydration state, serum electrolytes, and urine output 1
• Correct estimated fluid deficits within 24 hours 1
• Monitor closely for fluid overload in patients with renal or cardiac compromise 1

Insulin Therapy

Start continuous IV regular insulin infusion at 0.1 units/kg/hour without an initial bolus. 1

• If glucose does not fall by 50 mg/dL in the first hour, double the insulin infusion rate hourly until achieving a steady decline of 50-75 mg/dL per hour 1
• When glucose reaches 200-250 mg/dL, add dextrose to IV fluids while continuing insulin infusion to clear ketones 1, 3
• Continue insulin therapy until ketoacidosis resolves, regardless of glucose levels—premature termination before ketone clearance is a critical error 3

Transition to Subcutaneous Insulin

Administer basal subcutaneous insulin 2-4 hours before stopping IV insulin to prevent rebound hyperglycemia. 1

Potassium Replacement

If initial potassium <3.3 mEq/L, delay insulin therapy and aggressively replace potassium first to prevent fatal cardiac arrhythmias. 1

Once serum potassium <5.5 mEq/L and adequate urine output confirmed: 1

• Add 20-30 mEq potassium per liter of IV fluid 1
• Goal: maintain serum potassium 4-5 mEq/L 1
• Continue until patient can tolerate oral supplementation 1

Bicarbonate Therapy

Do not administer bicarbonate except when pH <6.9. 1 If needed, add to IV fluids rather than giving as bolus. 5

Monitoring During Treatment

Draw blood every 2-4 hours to measure: 1, 2

• Electrolytes 1
• Glucose 1
• Venous pH (arterial blood gases unnecessary after initial diagnosis) 1
• β-hydroxybutyrate 1
• Anion gap 1
• BUN/creatinine 1
• Serum osmolality 1

Venous pH adequately monitors acidosis resolution and is typically 0.03 units lower than arterial pH—avoid unnecessary arterial sticks. 1

Resolution Criteria

DKA is resolved when ALL of the following are met: 1, 2

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

Ketonemia typically takes longer to clear than hyperglycemia—continue monitoring β-OHB until normalized. 1

Special Monitoring Consideration

Monitor closely for cerebral edema during treatment, especially with overly aggressive fluid resuscitation, particularly in children. 1

Identify and Treat Precipitating Causes

Failing to identify and treat the underlying precipitating cause leads to DKA recurrence. 1 Common precipitants include:

• Infection 1
• Missed insulin doses 3
• New-onset diabetes 6
• Myocardial infarction 4
• Pancreatitis 4
• Medications (SGLT2 inhibitors, corticosteroids) 3

Patient Education for Prevention

Provide education on: 1

• Recognition of early DKA symptoms 1
• Sick-day management rules 4
• Never stopping basal insulin even when not eating 3
• Checking blood ketones when glucose >200 mg/dL or during illness 3
• Importance of medication compliance 6