What is the initial insulin dose and adjustment protocol for patients with Diabetic Ketoacidosis (DKA)?

Insulin Dose Adjustment in DKA

Start with continuous intravenous regular insulin at 0.1 units/kg/hour without an initial bolus for moderate to severe DKA, and double the infusion rate every hour if glucose does not fall by at least 50 mg/dL in the first hour. 1, 2

Initial Insulin Dosing

Adults and adolescents: Begin continuous IV regular insulin at 0.1 units/kg/hour (approximately 5-7 units/hour for most adults) once hypokalemia is excluded 2, 3. No initial bolus is recommended for moderate to severe DKA 2.

Pediatric patients (≤20 years): Start at 0.1 units/kg/hour without an initial bolus 1. The initial bolus is specifically not recommended in children due to increased risk of cerebral edema 1, 4.

Mild DKA alternative: For metabolically stable patients with mild DKA, subcutaneous or intramuscular insulin is equally effective 1. Give a priming dose of 0.4-0.6 units/kg (half IV, half SC/IM), then 0.1 units/kg/hour SC or IM 1, 2.

Monitoring the Initial Response

Monitor blood glucose hourly during the first few hours 2, 3. The expected glucose decline is 50-75 mg/dL/hour 1, 2.

If glucose fails to drop by 50 mg/dL in the first hour:

• First verify adequate hydration status 1, 2
• If hydration is acceptable, double the insulin infusion rate every hour until achieving steady glucose decline of 50-75 mg/dL/hour 1, 2

This aggressive titration approach is critical—do not hesitate to escalate the insulin dose if the initial response is inadequate 1.

Adjustment When Glucose Reaches Target

When serum glucose reaches 250 mg/dL (or 300 mg/dL in HHS):

• Decrease insulin infusion to 0.05-0.1 units/kg/hour 1, 2, 3
• Add dextrose (5-10%) to IV fluids 2, 5
• Continue insulin infusion at this reduced rate until ketoacidosis fully resolves 2, 5

Critical pitfall: Many clinicians mistakenly stop or excessively reduce insulin when glucose normalizes. This is the most common error leading to persistent or recurrent ketoacidosis 5. The goal is resolution of ketoacidosis (not just hyperglycemia), which requires continued insulin therapy 1, 2.

Monitoring During Treatment

Draw blood every 2-4 hours for: 1, 2, 3

• Serum electrolytes (especially potassium)
• Glucose
• Venous pH
• Anion gap
• BUN/creatinine

Ketone monitoring: Measure β-hydroxybutyrate directly if available—this is the preferred method 1, 2, 5. Do not rely on nitroprusside-based urine or serum ketone tests, as these only detect acetoacetate and acetone, not β-hydroxybutyrate (the predominant ketone in DKA) 1, 2. During treatment, β-hydroxybutyrate converts to acetoacetate, which can falsely suggest worsening ketosis 1.

Criteria for DKA Resolution

Continue insulin therapy until ALL of the following are met: 1, 2, 3

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

Important: Ketonemia typically takes longer to clear than hyperglycemia 1, 2, 5. Do not stop insulin based solely on glucose normalization.

Transition to Subcutaneous Insulin

Timing is critical: Administer basal insulin (glargine, detemir, or NPH) 2-4 hours before discontinuing IV insulin 1, 2, 3. This overlap prevents rebound hyperglycemia and recurrent ketoacidosis 1, 3.

When the patient can eat, initiate a multiple-dose regimen combining: 1, 2, 3

• Rapid-acting or short-acting insulin for meals
• Long-acting or intermediate-acting basal insulin

Continue IV insulin for 1-2 hours after starting the subcutaneous regimen to ensure adequate plasma insulin levels 1.

Special Considerations for Euglycemic DKA

In euglycemic DKA (glucose <250 mg/dL with ketoacidosis): 5

• Start insulin at 0.1 units/kg/hour as usual
• Immediately add dextrose to IV fluids while continuing insulin
• The insulin must continue until ketoacidosis resolves, regardless of glucose levels
• This scenario commonly occurs with SGLT2 inhibitor use, pregnancy, or reduced carbohydrate intake

Electrolyte Management During Insulin Therapy

Potassium: Insulin drives potassium intracellularly, causing potentially dangerous hypokalemia 2, 3, 4. Add 20-30 mEq/L potassium (2/3 KCl, 1/3 KPO4) to IV fluids once urine output is established and serum potassium is <5.3 mEq/L 1, 3. Monitor potassium closely and maintain levels between 4-5 mEq/L 5.

Bicarbonate: Generally not recommended unless pH <6.9 1, 2, 3. Studies show no benefit in DKA resolution or outcomes, and bicarbonate may increase cerebral edema risk in children 1, 4.

Common Pitfalls to Avoid

• Stopping IV insulin prematurely: This is the single most common error causing DKA recurrence 5, 3. Always overlap with subcutaneous basal insulin.
• Reducing insulin too much when glucose normalizes: Continue at 0.05-0.1 units/kg/hour with dextrose until ketoacidosis resolves 2, 5.
• Inadequate potassium monitoring: Hypokalemia can be life-threatening during insulin therapy 2, 3, 4.
• Using nitroprusside ketone tests: These are misleading during treatment 1, 2.
• Insufficient hydration before insulin escalation: Always verify adequate fluid resuscitation before doubling insulin doses 1, 2.