When to Start Overlap Insulin Management in DKA
Administer basal subcutaneous insulin (glargine or detemir) 2-4 hours BEFORE stopping the IV insulin infusion to prevent recurrence of ketoacidosis and rebound hyperglycemia. 1
Timing of Transition: The Critical Window
The overlap period is initiated once DKA has resolved, defined by ALL of the following criteria being met 2, 3:
- Glucose <200 mg/dL
- Serum bicarbonate ≥18 mEq/L
- Venous pH >7.3
The most common and dangerous error is stopping IV insulin without prior basal insulin administration—this leads directly to DKA recurrence. 1
Step-by-Step Overlap Protocol
Step 1: Confirm DKA Resolution
Monitor every 2-4 hours until all three resolution criteria are simultaneously met 2, 3. Do not rely on glucose normalization alone, as ketonemia takes longer to clear than hyperglycemia 3.
Step 2: Administer Basal Insulin First
Give subcutaneous basal insulin (glargine or detemir) at an appropriate dose 2-4 hours before discontinuing IV insulin 1. This timing ensures adequate plasma insulin levels are maintained during the transition 3.
Step 3: Continue IV Insulin During Overlap
Maintain the IV insulin infusion for 1-2 hours after administering subcutaneous basal insulin 3. This overlap prevents the insulin-free gap that causes ketoacidosis recurrence.
Step 4: Add Rapid-Acting Insulin if Eating
When the patient can eat, initiate a multiple-dose schedule combining short/rapid-acting insulin with the basal insulin 2, 3.
Management While NPO After DKA Resolution
If the patient remains NPO after DKA resolves, continue IV insulin and fluid replacement, supplementing with subcutaneous regular insulin every 4 hours as needed 2, 3:
- Give 5-unit increments for every 50 mg/dL increase in blood glucose above 150 mg/dL
- Maximum 20 units for blood glucose of 300 mg/dL 2, 3
Critical Monitoring During Transition
Continue monitoring potassium closely during the overlap period, as insulin drives potassium intracellularly. 1 Maintain serum potassium between 4-5 mEq/L with appropriate supplementation 3.
Check electrolytes, glucose, and venous pH every 2-4 hours until stable on subcutaneous insulin 3.
Common Pitfalls to Avoid
The evidence consistently identifies stopping IV insulin without prior basal insulin as the primary cause of treatment failure 1. The 2-4 hour overlap window is not arbitrary—it accounts for the pharmacokinetic delay in achieving therapeutic levels of long-acting insulin 1, 3.
Do not be misled by glucose normalization alone; continue IV insulin until all three resolution criteria are met, then implement the overlap protocol 2, 3.