What is the recommended initial insulin dose for a patient with Diabetic Ketoacidosis (DKA)?

Insulin Dosing for Diabetic Ketoacidosis (DKA)

Start continuous intravenous regular insulin at 0.1 units/kg/hour without an initial bolus for adults and children with moderate to severe DKA, which translates to approximately 5-7 units/hour for most adults. 1, 2

Initial Insulin Regimen

Standard IV Insulin Protocol

• Administer 0.1 units/kg/hour as a continuous IV infusion of regular insulin once you have confirmed serum potassium is ≥3.3 mEq/L 1, 2
• Do NOT give an initial bolus dose in pediatric patients, as this increases the risk of cerebral edema 3
• For adults with mild DKA only, you may use subcutaneous or intramuscular regular insulin instead: give a priming dose of 0.4-0.6 units/kg (half IV bolus, half SC/IM), then 0.1 units/kg/hour SC or IM 3, 1

Critical Pre-Insulin Safety Check

• Never start insulin if potassium is <3.3 mEq/L - this is an absolute contraindication that can cause fatal cardiac arrhythmias 2
• If potassium is low, aggressively replete with 20-40 mEq/L in IV fluids until K+ reaches ≥3.3 mEq/L, then start insulin 2

Monitoring and Dose Adjustment

Expected Response

• Plasma glucose should decrease by 50-75 mg/dL per hour with this low-dose regimen 3, 1
• Check blood glucose every 1-2 hours during active treatment 1

If Glucose Isn't Falling Adequately

• If plasma glucose does not fall by at least 50 mg/dL in the first hour, verify hydration status is adequate 3
• Double the insulin infusion rate every hour until you achieve a steady glucose decline of 50-75 mg/dL per hour 3, 1

When Glucose Reaches 250 mg/dL

• Reduce insulin infusion to 0.05-0.1 units/kg/hour 1
• Add dextrose (D5) to IV fluids to prevent hypoglycemia 1, 2
• Continue insulin at this reduced rate until ketoacidosis resolves, NOT just until glucose normalizes - ketonemia takes longer to clear than hyperglycemia 3, 1

Resolution Criteria and Transition

DKA Resolution Defined As:

• Glucose <200 mg/dL AND
• Serum bicarbonate ≥18 mEq/L AND
• Venous pH >7.3 AND
• Anion gap ≤12 mEq/L 1, 4, 2

Transitioning to Subcutaneous Insulin

• Administer the first dose of subcutaneous basal insulin (glargine or detemir) 2-4 hours BEFORE stopping the IV insulin - this is the most critical step to prevent rebound hyperglycemia and recurrent DKA 4, 2
• Calculate basal insulin dose as 50% of total daily dose, which can be estimated as: (average hourly IV insulin rate over last 12 hours) × 24 hours × 0.5 4
• Alternatively, use 0.5 units/kg/day as total daily dose, with 50% given as basal insulin 4
• Add prandial rapid-acting insulin (lispro, aspart, or glulisine) as the other 50% of total daily dose, divided before meals 4

Common Pitfalls to Avoid

• Never stop IV insulin abruptly without prior subcutaneous basal insulin - this is the most common error causing DKA recurrence 4, 2
• Never use correction-only (sliding scale) insulin alone - this approach leads to worse outcomes and higher complication rates 4, 2
• Do not rely on urine ketones measured by nitroprusside method to assess treatment response, as this method doesn't measure β-hydroxybutyrate (the predominant ketone) and can falsely suggest worsening ketosis during treatment 3, 1
• Monitor potassium closely throughout treatment, as insulin drives potassium intracellularly and can cause dangerous hypokalemia 3, 2
• Add 20-30 mEq/L potassium to IV fluids once K+ is 3.3-5.5 mEq/L and urine output is adequate 4, 2

Special Considerations

Pediatric Patients

• Use the same 0.1 units/kg/hour continuous IV infusion without an initial bolus 3
• When glucose reaches 250 mg/dL in DKA (or 300 mg/dL in HHS), continue insulin at 0.1 units/kg/hour 3
• Low-dose insulin (0.1 units/kg/hour) is as effective as high-dose (1.0 units/kg/hour) with significantly less hypokalemia and hypoglycemia risk 5

Alternative for Mild DKA

• Subcutaneous rapid-acting insulin aspart at 0.15 units/kg every 2 hours is an effective alternative to IV regular insulin for mild to moderate DKA, with faster recovery and shorter hospital stays 6