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

Diabetic Ketoacidosis: Diagnosis and Treatment

Diagnostic Criteria

DKA is diagnosed when all three criteria are present: blood glucose >250 mg/dL (though euglycemic DKA exists), venous pH <7.3, serum bicarbonate <15 mEq/L, and moderate ketonuria or ketonemia. 1

Essential Laboratory Evaluation

• Obtain immediately: complete metabolic panel, venous blood gases, complete blood count, urinalysis, and direct measurement of β-hydroxybutyrate in blood (not urine ketones or nitroprusside methods, which miss the predominant ketoacid) 1
• Calculate anion gap using [Na⁺] - ([Cl⁻] + [HCO₃⁻]); should be >10-12 mEq/L in DKA 1
• Correct serum sodium for hyperglycemia: add 1.6 mEq/L for every 100 mg/dL glucose above 100 1
• Obtain bacterial cultures (urine, blood, throat) if infection suspected, plus chest X-ray if clinically indicated 2

Severity Classification

• Mild DKA: pH 7.25-7.30, bicarbonate 15-18 mEq/L, alert mental status 1
• Moderate DKA: pH 7.00-7.24, bicarbonate 10-15 mEq/L, drowsy mental status 1
• Severe DKA: pH <7.00, bicarbonate <10 mEq/L, stupor/coma; requires intensive monitoring including possible central venous and intra-arterial pressure monitoring 1

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Treatment Protocol

Step 1: Fluid Resuscitation (FIRST PRIORITY)

Begin aggressive fluid resuscitation with isotonic saline at 15-20 mL/kg/hour for the first hour to restore circulatory volume and tissue perfusion. 3

• Total fluid replacement should correct estimated deficits within 24 hours 1
• After initial volume expansion, subsequent fluid choice depends on hydration status, serum electrolytes, and urine output 3
• When serum glucose reaches 250 mg/dL, change fluid to 5% dextrose with 0.45-0.75% NaCl while continuing insulin therapy to resolve ketosis 3
• Monitor closely for fluid overload in patients with renal or cardiac compromise 1

Step 2: Potassium Management (BEFORE INSULIN)

Critical: Do NOT start insulin if serum potassium is <3.3 mEq/L—this can cause life-threatening cardiac arrhythmias and death. 2

• If K⁺ <3.3 mEq/L: Hold insulin, continue isotonic saline, and aggressively replace potassium with 20-40 mEq/L IV until K⁺ ≥3.3 mEq/L 2
• Once K⁺ ≥3.3 mEq/L and adequate urine output confirmed: Add 20-30 mEq/L potassium (2/3 KCl and 1/3 KPO₄) to IV fluids 3
• Target: Maintain serum potassium 4-5 mEq/L throughout treatment 3
• Obtain ECG to assess cardiac effects of hypokalemia 2

Step 3: Insulin Therapy

For adults with moderate to severe DKA: Administer IV bolus of regular insulin at 0.15 units/kg body weight (after confirming K⁺ ≥3.3 mEq/L), followed by continuous infusion at 0.1 units/kg/hour. 3

• Pediatric exception: Do NOT give initial bolus in children; start directly with continuous infusion at 0.1 units/kg/hour 3
• For mild DKA: Subcutaneous rapid-acting insulin analogs combined with aggressive fluid management can be as effective as IV insulin 3
• If glucose does not fall by 50 mg/dL in the first hour, check hydration status; if acceptable, double the insulin infusion rate hourly until achieving steady decline of 50-75 mg/dL per hour 3
• Continue insulin therapy until resolution of ketoacidosis (pH >7.3, bicarbonate ≥18 mEq/L, anion gap ≤12 mEq/L) regardless of glucose levels 3

Step 4: Monitoring During Treatment

Draw blood every 2-4 hours to measure glucose, electrolytes, BUN, creatinine, osmolality, venous pH, and β-hydroxybutyrate. 3

• Follow venous pH and anion gap to monitor acidosis resolution (venous pH typically 0.03 units lower than arterial; repeat arterial sticks are unnecessary after initial diagnosis) 1
• Pitfall to avoid: Do not use nitroprusside-based ketone tests (urine or serum) for monitoring—they only measure acetoacetate and acetone, completely missing β-hydroxybutyrate, and paradoxically appear worse as patient improves during treatment 1
• Ketonemia typically takes longer to clear than hyperglycemia 3

Step 5: Resolution Criteria

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

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

Step 6: Transition to Subcutaneous Insulin

Administer basal insulin (glargine or detemir) 2-4 hours BEFORE stopping IV insulin infusion to prevent recurrence of ketoacidosis and rebound hyperglycemia. 3

• Recent studies suggest adding low-dose basal insulin analog during IV insulin infusion may prevent rebound hyperglycemia without increased hypoglycemia risk 3
• Most common error: Stopping IV insulin without prior basal insulin administration leads to DKA recurrence 2

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Special Considerations

Bicarbonate Therapy

Bicarbonate therapy is NOT recommended for DKA management, except when pH <6.9. 1

Cerebral Edema Risk

• Monitor closely for cerebral edema, especially with overly aggressive fluid resuscitation 1
• This complication is more common in pediatric patients 1

Underlying Precipitating Causes

Identify and treat any correctable underlying cause (sepsis, myocardial infarction, stroke, medication non-adherence) to prevent recurrence. 3

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Discharge Planning

• Develop structured discharge plan tailored to the patient, including medication reconciliation 3
• Provide education on recognition, prevention, and management of DKA 1
• Schedule follow-up appointments prior to discharge to increase attendance likelihood 3
• Transmit discharge summaries to primary care clinician as soon as possible 3