Insulin Dosing for Hyperglycemia (≥250 mg/dL)
For adults with significant hyperglycemia (≥250 mg/dL), initiate a basal-bolus insulin regimen with a total daily dose of 0.3-0.5 U/kg, divided equally between basal insulin (once or twice daily) and rapid-acting insulin (before meals), as this approach reduces complications including infections, respiratory failure, and acute kidney injury compared to sliding scale insulin alone. 1
Dosing Algorithm by Clinical Context
For Insulin-Naive Patients or Low Home Insulin Use
- Start with 0.3-0.5 U/kg/day total daily dose (TDD)
- Split 50/50: half as basal insulin, half as rapid-acting insulin divided before three meals
- Add correctional doses of rapid-acting insulin for breakthrough hyperglycemia 1
For Patients on High-Dose Home Insulin (≥0.6 U/kg/day)
- Reduce home TDD by 20% to prevent hypoglycemia from reduced oral intake in hospital
- Maintain basal-bolus structure 1
For High-Risk Patients (Age >65, Renal Failure, Poor Oral Intake)
- Use lower starting doses: 0.15-0.3 U/kg/day
- Consider basal-plus approach (single basal dose 0.1-0.25 U/kg/day plus correctional insulin) rather than full basal-bolus 1
Critical Distinctions
Avoid sliding scale insulin alone in patients with established diabetes—it is associated with worse glycemic control and higher complication rates. The basal-bolus approach reduces composite complications (wound infections, pneumonia, bacteremia, renal/respiratory failure) compared to sliding scale monotherapy 1. However, sliding scale alone may be appropriate for patients without diabetes who have mild stress hyperglycemia 1.
Never use sliding scale insulin alone in Type 1 diabetes—these patients require continuous insulin coverage 1.
Hypoglycemia Risk Management
The basal-bolus approach carries 4-6 times higher hypoglycemia risk than sliding scale insulin (risk ratio 5.75 for glucose ≤70 mg/dL) 1. To mitigate this:
- Withhold prandial insulin if patient has poor oral intake
- Use basal-plus regimen (basal insulin + correctional doses only) for fasting patients or those with unpredictable intake 1
- Monitor glucose before meals and adjust accordingly
Critically Ill Patients
For ICU patients or those with severe hyperglycemia requiring intensive management:
- Use continuous intravenous insulin infusion with target glucose 140-180 mg/dL 2
- Transition to subcutaneous insulin only when stable (off vasopressors, stable nutrition, consistent insulin requirements for 4-6 hours) 1, 3
- Calculate subcutaneous TDD from average hourly IV insulin rate over preceding 12 hours (e.g., 1.5 U/hour × 24 = 36 U/day) 1
Key Pitfalls to Avoid
- Premixed insulin (70/30) is not recommended in hospital settings due to unacceptably high hypoglycemia rates 1
- Do not abruptly stop basal insulin when transitioning off IV insulin—this causes rebound hyperglycemia 3
- Account for nutritional status: adjust insulin doses if enteral/parenteral nutrition is interrupted or discontinued 3
- For glucose >300 mg/dL (16.6 mmol/L), more aggressive basal-bolus regimens are mandatory rather than simplified approaches 1