What is the recommended management of diabetic ketoacidosis, including fluid resuscitation, insulin therapy, potassium replacement, monitoring, and transition to subcutaneous insulin?

Management of Diabetic Ketoacidosis

Begin immediate fluid resuscitation with isotonic saline at 15–20 mL/kg/hour for the first hour, followed by continuous IV regular insulin at 0.1 units/kg/hour (after confirming potassium ≥3.3 mEq/L), aggressive potassium replacement targeting 4–5 mEq/L, and transition to subcutaneous basal insulin 2–4 hours before stopping the IV infusion. 1, 2

Initial Assessment and Laboratory Evaluation

Obtain the following immediately upon presentation:

• Plasma glucose, serum ketones (preferably β-hydroxybutyrate), electrolytes with calculated anion gap, venous blood gas (not arterial unless clinically indicated), blood urea nitrogen, creatinine, serum osmolality 1, 2
• Complete blood count with differential, urinalysis with urine ketones, electrocardiogram 3, 1
• Bacterial cultures (blood, urine, throat) and chest X-ray only if infection is suspected or clinically indicated—not routinely 3, 4

Calculate corrected sodium: add 1.6 mEq/L to measured sodium for every 100 mg/dL glucose above 100 mg/dL 3

Fluid Resuscitation Protocol

Hour 1: Administer isotonic saline (0.9% NaCl) at 15–20 mL/kg body weight/hour 3, 1, 2

Subsequent hours:

• If corrected sodium is normal or elevated: switch to 0.45% NaCl at 4–14 mL/kg/hour 3
• If corrected sodium is low: continue 0.9% NaCl at similar rate 3
• Total fluid replacement should approximate 1.5 times the 24-hour maintenance requirement 1

When glucose reaches 250 mg/dL: Change to 5% dextrose with 0.45–0.75% NaCl while continuing insulin infusion at the same rate 3, 1

Insulin Therapy

Critical Pre-Insulin Check

Do not start insulin if serum potassium is <3.3 mEq/L—this is an absolute contraindication that can cause life-threatening cardiac arrhythmias and death 1, 5. Aggressively replete potassium first until K⁺ ≥3.3 mEq/L 1

Standard IV Insulin Protocol (Moderate-Severe DKA)

• IV bolus: 0.1 units/kg regular insulin as direct push 1, 2
• Continuous infusion: 0.1 units/kg/hour regular insulin via IV pump 3, 1, 2
• Preparation: Add 100 units regular insulin to 100 mL normal saline (1 unit/mL concentration); prime tubing with 20 mL before connecting to patient 1
• Target glucose decline: 50–75 mg/dL per hour 1, 2

If glucose does not fall by 50 mg/dL in the first hour: Verify adequate hydration, then double the insulin infusion rate every hour until achieving steady decline of 50–75 mg/dL/hour 1

Alternative Subcutaneous Protocol (Mild-Moderate Uncomplicated DKA Only)

For hemodynamically stable, alert patients with mild-moderate DKA:

• Subcutaneous rapid-acting insulin analogs (0.1–0.2 units/kg every 1–2 hours) combined with aggressive IV fluid replacement can be as effective and more cost-effective than IV insulin 1, 2
• Requires frequent bedside glucose monitoring and appropriate follow-up 1

Pediatric Considerations

• No initial bolus in children <20 years 3
• Start continuous infusion at 0.05–0.1 units/kg/hour to reduce hypokalemia risk 1
• Initial fluid resuscitation: 10–20 mL/kg/hour isotonic saline, not exceeding 50 mL/kg over first 4 hours to minimize cerebral edema risk 3

Potassium Replacement Strategy

Potassium Thresholds (Class A Evidence)

• K⁺ <3.3 mEq/L: Hold insulin; aggressively replete potassium until ≥3.3 mEq/L 1, 2, 5
• K⁺ 3.3–5.5 mEq/L: Start insulin; add 20–30 mEq/L potassium to IV fluids once urine output is adequate 3, 1, 2
• K⁺ >5.5 mEq/L: Start insulin immediately; delay potassium supplementation until level falls below 5.5 mEq/L 1

Potassium Formulation

Use 2/3 KCl (or potassium-acetate) and 1/3 KPO₄ in each liter of IV fluid 3, 1, 5

Target and Monitoring

• Target range: 4.0–5.0 mEq/L throughout treatment 1, 2, 5
• Monitoring frequency: Every 2–4 hours until stable 1, 2
• Rationale: Insulin drives potassium intracellularly; total body potassium deficit averages 1.0 mmol/kg despite normal or elevated initial levels 1

Bicarbonate Therapy (Rarely Indicated)

• pH ≥7.0: No bicarbonate necessary—insulin therapy alone is sufficient 2, 5
• pH 6.9–7.0: Prospective randomized studies show no benefit or harm; bicarbonate not recommended 5
• pH <6.9: May consider bicarbonate in adults only (Grade B recommendation) 5

Common pitfall: Do not administer bicarbonate based solely on low HCO₃⁻; pH is the determining factor 5

Monitoring Parameters

Check every 2–4 hours until stable:

• Blood glucose (bedside and laboratory) 1, 2, 5
• Serum electrolytes (especially potassium) 1, 2, 5
• Venous pH 1, 2, 5
• Serum bicarbonate and anion gap 1, 2
• Blood urea nitrogen, creatinine, serum osmolality 1, 2

DKA Resolution Criteria

All of the following must be met simultaneously:

• Glucose <200 mg/dL 1, 5
• Serum bicarbonate ≥18 mEq/L 1, 2, 5
• Venous pH >7.3 1, 2, 5
• Anion gap ≤12 mEq/L 1
• Patient able to tolerate oral intake 1

Transition to Subcutaneous Insulin

Timing and Overlap Protocol (Critical to Prevent DKA Recurrence)

Administer long-acting basal insulin (glargine or detemir) subcutaneously 2–4 hours BEFORE discontinuing the IV insulin infusion—this is the single most important step to prevent rebound DKA 1, 2, 5

Continue IV insulin infusion for 1–2 hours after administering subcutaneous basal insulin to ensure adequate absorption and prevent coverage gap 1, 2

Dose Calculation

• Basal insulin: Use 50% of the total 24-hour IV insulin amount as a single daily dose of long-acting insulin 1
• Prandial insulin: Divide the remaining 50% of the 24-hour IV insulin amount equally among three meals as rapid-acting insulin 1

Common Pitfall to Avoid

Never stop IV insulin without prior basal insulin administration—this is the most common error leading to DKA recurrence 1, 2. Stopping IV insulin abruptly without overlap creates a coverage gap that precipitates ketoacidosis within hours 1

Special Considerations

Euglycemic DKA

When initial glucose is <250 mg/dL, start 5% dextrose with normal saline from the outset of insulin therapy while continuing insulin infusion to clear ketones 1

Glucose Management During Treatment

Never hold insulin when glucose falls to target—instead add dextrose to IV fluid while maintaining insulin infusion at 0.1 units/kg/hour to continue clearing ketones 1, 5. Target glucose range of 150–200 mg/dL until full resolution of ketoacidosis 1

Monitoring Mental Status

Particularly in pediatric patients, continuously assess mental status to rapidly identify changes suggesting cerebral edema or other iatrogenic complications 3