Insulin Dosing for DKA in a 13-Year-Old: Add 10 Units Regular Insulin to 1 Liter Normal Saline
For a 13-year-old patient with diabetic ketoacidosis, add 10 units of regular insulin to 1 liter of plain normal saline (0.9% NaCl) to create a standard concentration of 0.1 units/mL for continuous intravenous infusion. This concentration allows for precise titration based on the patient's weight and clinical response 1, 2.
Standard Insulin Concentration Preparation
- The standard concentration is 100 units of regular insulin in 100 mL of normal saline (1 unit/mL), which can be proportionally adjusted to 10 units in 1 liter (0.1 units/mL) 1, 2
- This dilution allows for accurate dosing when using standard infusion pumps and facilitates weight-based calculations 1
Initial Dosing Protocol for Pediatric DKA
Critical Pre-Insulin Safety 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 1
- Begin aggressive potassium repletion with 20-40 mEq/L added to IV fluids until K+ ≥3.3 mEq/L 1, 2
Insulin Infusion Initiation
- For pediatric patients, start continuous IV infusion at 0.1 units/kg/hour WITHOUT an initial bolus dose 2
- Do NOT give a bolus dose in children—this differs from adult protocols and reduces the risk of cerebral edema 2
- Target glucose decline of 50-75 mg/dL per hour 1, 2
Infusion Rate Adjustments
If Glucose Doesn't Decline Adequately
- If plasma glucose does not fall by 50 mg/dL in the first hour, verify adequate hydration status 1, 2
- If hydration is acceptable, double the insulin infusion rate hourly until achieving steady glucose decline of 50-75 mg/dL/hour 1, 2
When Glucose Reaches 250 mg/dL
- Add dextrose 5% to the IV fluids when serum glucose falls to 250 mg/dL while continuing insulin infusion 3, 2
- This prevents hypoglycemia while allowing continued insulin therapy to resolve ketoacidosis 3, 2
- Target glucose maintenance between 150-200 mg/dL until DKA fully resolves 3, 2
Critical Monitoring Parameters
Laboratory Monitoring
- Check blood glucose every 2-4 hours 1, 2
- Draw serum electrolytes, glucose, BUN, creatinine, osmolality, and venous pH every 2-4 hours until stable 1, 2
- Maintain serum potassium between 4-5 mmol/L throughout treatment 1, 2
DKA Resolution Criteria
All of the following must be met before transitioning off IV insulin: 3, 2
- Glucose <200 mg/dL
- Serum bicarbonate ≥18 mEq/L
- Venous pH >7.3
- Anion gap ≤12 mEq/L
Common Pitfalls to Avoid
Premature Insulin Discontinuation
- Never stop IV insulin without administering subcutaneous basal insulin 2-4 hours beforehand—this is the most common error leading to DKA recurrence 1, 2
- Continue IV insulin for 1-2 hours after giving subcutaneous insulin to ensure adequate plasma levels 1, 2
Inadequate Insulin During Resolution Phase
- Ketonemia takes longer to clear than hyperglycemia—continue insulin infusion until all resolution criteria are met, not just glucose normalization 3, 2
- Do not reduce insulin rate prematurely when glucose normalizes; instead add dextrose to IV fluids 3, 2
Potassium Management Errors
- Insulin drives potassium intracellularly, causing potentially dangerous hypokalemia 1, 2
- Add 20-30 mEq/L potassium (using 2/3 KCl and 1/3 KPO₄) to each liter of IV fluid once renal function is confirmed 1, 2
Special Considerations for Severe or Refractory Cases
- In rare cases of severe DKA unresponsive to standard dosing (0.1 units/kg/hour), insulin rates may need to be increased to 0.14-0.15 units/kg/hour 4, 5, 6
- Some patients with severe insulin resistance may require rates up to 4-6 units/hour or higher with appropriate glucose supplementation 6
- Always investigate underlying causes such as infection, inadequate initial dosing, or interruption of therapy if DKA fails to resolve 3