Timing of Insulin Initiation in DKA
Do not start insulin until after initial fluid resuscitation has begun and potassium levels are confirmed to be ≥3.3 mEq/L. 1
Critical Pre-Insulin Requirements
Potassium Level Must Be Checked First
- Insulin therapy must be delayed if serum potassium is <3.3 mEq/L to prevent life-threatening arrhythmias, cardiac arrest, and respiratory muscle weakness 1
- Potassium replacement should begin immediately with fluid therapy in hypokalemic patients, and insulin is withheld until potassium reaches at least 3.3 mEq/L 1
- This is non-negotiable—insulin drives potassium intracellularly and will worsen existing hypokalemia 2
Fluid Resuscitation Should Begin First
- Initial fluid therapy is directed toward expansion of intravascular volume and restoration of renal perfusion before insulin administration 1
- The first hour should focus on isotonic saline (0.9% NaCl) at 15-20 ml/kg/h (approximately 1-1.5 liters in the first hour for adults) 1
- Once hypovolemia is addressed and potassium is confirmed ≥3.3 mEq/L, insulin can be safely initiated 1
Insulin Initiation Protocol
For Adults with Moderate-to-Severe DKA
- After fluid resuscitation has begun and potassium is adequate, give an IV bolus of regular insulin at 0.15 units/kg, followed immediately by continuous IV infusion at 0.1 units/kg/hour 2
- This typically translates to approximately 5-7 units/hour for most adults 2
For Pediatric Patients
- Do not use an initial insulin bolus in children 2
- Begin directly with continuous IV infusion at 0.1 units/kg/hour after fluid resuscitation and potassium confirmation 2
Common Pitfalls to Avoid
Starting Insulin Too Early
- Starting insulin before adequate fluid resuscitation can worsen hypotension and shock 1
- Starting insulin with potassium <3.3 mEq/L risks fatal cardiac arrhythmias 1
Monitoring During Initial Phase
- Check potassium levels before starting insulin and monitor every 2-4 hours thereafter 2
- Once insulin is started, potassium will fall rapidly—maintain levels at 4-5 mEq/L by adding 20-30 mEq potassium per liter of IV fluid 1
- Monitor glucose every 1-2 hours initially; if glucose doesn't fall by at least 50 mg/dL in the first hour, verify hydration status and double the insulin infusion rate 2
Practical Timeline
- Hour 0-1: Begin aggressive fluid resuscitation with 0.9% NaCl, obtain STAT labs including potassium 1
- Once potassium ≥3.3 mEq/L confirmed: Start insulin infusion (with or without bolus depending on age) 1, 2
- If potassium <3.3 mEq/L: Continue fluids with potassium supplementation, recheck potassium, delay insulin 1