What is the appropriate management and administration of insulin for a 13-year-old patient with diabetic ketoacidosis (DKA) and altered mental status?

Management of Insulin Administration in Pediatric Diabetic Ketoacidosis

For a 13-year-old with DKA and altered mental status, start continuous IV regular insulin at 0.1 units/kg/hour WITHOUT a bolus dose, but only AFTER initiating aggressive fluid resuscitation and confirming serum potassium is ≥3.3 mEq/L. 1, 2, 3

Critical Pre-Insulin Requirements

Fluid Resuscitation MUST Precede Insulin

• Begin with isotonic (0.9%) saline at 15-20 mL/kg/hour for the first hour to restore circulatory volume before starting insulin 4, 1, 2
• Fluid administration should precede insulin by 1-2 hours to prevent precipitous drops in glucose that can worsen cerebral edema risk 5
• Total fluid replacement should approximate 1.5 times the 24-hour maintenance requirements 2, 3

Mandatory Potassium Assessment

• NEVER start insulin if serum potassium is <3.3 mEq/L - this is an absolute contraindication that can cause fatal cardiac arrhythmias and respiratory paralysis 1, 2, 6
• If K+ <3.3 mEq/L: Hold insulin, aggressively replace potassium first with 20-40 mEq/L in IV fluids, and obtain an ECG 1, 2
• Once K+ is 3.3-5.5 mEq/L and adequate urine output confirmed: Add 20-30 mEq/L potassium to IV fluids using 2/3 KCl and 1/3 KPO4 1, 2, 3
• Target serum potassium of 4-5 mEq/L throughout treatment, as insulin drives potassium intracellularly 3, 6

Insulin Administration Protocol

Initial Dosing

• Start continuous IV infusion of regular insulin at 0.1 units/kg/hour 4, 1, 2, 3
• Do NOT give an initial bolus in pediatric patients with altered mental status, as this differs from adult protocols 2, 3
• Use only regular insulin (NOT rapid-acting analogs) for IV infusion 2, 6

What to Mix Insulin With

• Regular insulin is administered as a continuous IV infusion in 0.9% normal saline 2, 6
• The insulin infusion runs separately from the primary fluid resuscitation line 2
• Typical preparation: 100 units regular insulin in 100 mL normal saline (1 unit/mL concentration) 2

Target Glucose Decline

• Aim for glucose to fall at 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 hourly until achieving steady decline 1, 2

Critical Monitoring Requirements

Frequent Laboratory Assessment

• Check blood glucose every 2-4 hours (or hourly initially) 1, 2, 3
• Measure serum electrolytes, BUN, creatinine, osmolality, and venous pH every 2-4 hours 1, 2, 3
• Monitor β-hydroxybutyrate if available (preferred over urine ketones) 1, 2
• Venous pH is adequate for monitoring after initial diagnosis - repeated arterial sticks are unnecessary 1

Neurological Monitoring for Cerebral Edema

• Monitor closely for signs of cerebral edema: worsening mental status, severe headache, recurrent vomiting, bradycardia, hypertension 1, 3
• This is the most feared complication in pediatric DKA with altered mental status 5, 7
• Have mannitol (0.5-1 g/kg IV) or 3% hypertensive saline (2.5-5 mL/kg) immediately available 1

Glucose Management During Treatment

When Glucose Falls to 200-250 mg/dL

• Do NOT stop insulin - this is a critical error that causes DKA recurrence 1, 2
• Add dextrose (5-10%) to IV fluids to prevent hypoglycemia while continuing insulin infusion 4, 1, 2
• Continue insulin at 0.05-0.1 units/kg/hour until complete resolution of ketoacidosis 2

DKA Resolution Criteria

All of the following must be met simultaneously: 1, 2

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

Transition to Subcutaneous Insulin

Critical Timing to Prevent Recurrence

• Administer basal subcutaneous insulin (glargine or detemir) 2-4 hours BEFORE stopping the IV insulin infusion 1, 2, 3
• This overlap is essential - stopping IV insulin without prior subcutaneous basal insulin is the most common error leading to DKA recurrence 2
• Continue IV insulin for 1-2 hours after giving subcutaneous insulin to allow for absorption 2

Post-Resolution Management

• Once acidosis resolves and patient can tolerate oral intake, initiate metformin while continuing subcutaneous insulin 4
• Start a multiple-dose insulin regimen with basal and prandial components 4, 2
• In patients initially treated with insulin who meet glucose targets, insulin can be tapered over 2-6 weeks by decreasing dose 10-30% every few days 4

Common Pitfalls to Avoid

• Never use rapid-acting insulin analogs (lispro, aspart, glulisine) for IV infusion - only regular insulin is appropriate 2, 6
• Never give insulin intramuscularly or subcutaneously in severe DKA with altered mental status - IV route is mandatory 3, 6
• Never use bicarbonate therapy unless pH <6.9, as it provides no benefit and may worsen outcomes 1, 2
• Never rely on urine ketones for monitoring - they measure acetoacetate, not β-hydroxybutyrate, and can falsely suggest worsening during treatment 1
• Never stop IV insulin when glucose normalizes - ketoacidosis takes longer to resolve than hyperglycemia 1, 2, 3