When should a sliding scale of regular (Novolin R or Humulin R) insulin be used?

When to Use Sliding Scale with Regular Insulin

Sliding scale insulin (SSI) should not be used as the sole method of glycemic control in hospitalized patients, but rather should be used as a supplementary correction component alongside basal or basal-bolus insulin regimens. 1, 2

Appropriate Use of Sliding Scale Regular Insulin

Primary Indications

• As a correctional component of a comprehensive insulin regimen that includes:
  • Basal insulin (long-acting)
  • Prandial insulin (if patient is eating)
  • Correctional insulin (sliding scale) 1, 2

Specific Clinical Scenarios

1. During prandial insulin adjustment:

   • While adjusting prandial insulin doses in patients transitioning to a basal-bolus regimen 1
   • Example simplified sliding scale during adjustment:
     • For premeal glucose >250 mg/dL: add 2 units of regular insulin
     • For premeal glucose >350 mg/dL: add 4 units of regular insulin 1

2. For patients with unpredictable oral intake:

   • When patients have variable or poor oral intake
   • When immediate post-meal administration is safer (administer regular insulin after seeing what patient actually consumed) 1

3. As temporary coverage:

   • During transitions of care (e.g., from IV to subcutaneous insulin)
   • During acute illness with fluctuating insulin requirements 2

Contraindications and Cautions

Not Recommended As:

• Sole therapy for inpatient glycemic control - The American Diabetes Association strongly discourages the sole use of sliding scale insulin in hospitalized patients 1, 2
• Long-term management strategy - Prolonged use of SSI alone is associated with:
  • Poor glycemic control 3, 4
  • Higher mean blood glucose levels (14.8 mg/dL higher than basal-bolus regimens) 3
  • Increased glycemic variability 5

Evidence Against Sole SSI Use

• Multiple studies show that sliding scale insulin alone is ineffective:
  • Only 12% of sliding scale insulin injections successfully brought glucose levels to target range in one study 5
  • 84% of sliding scale insulin injections were subtherapeutic 5
  • Basal-bolus regimens provide better glycemic control than SSI alone 3

Proper Implementation of Sliding Scale Regular Insulin

Timing Considerations

• Regular insulin should be administered 30 minutes before meals when used as scheduled prandial insulin 6
• When used as correctional insulin:
  • Administer based on pre-meal blood glucose readings for patients who are eating 1
  • Every 4-6 hours for patients on continuous feeding or NPO 2

Dosing Guidelines

• Correctional insulin should be added based on standardized scales according to insulin sensitivity 2:

  Blood Glucose (mg/dL)	Low-Dose Scale	Moderate-Dose Scale	High-Dose Scale
  140-180	1 unit	2 units	3 units
  181-220	2 units	4 units	6 units

Best Practices for Hospital Glycemic Management

Recommended Approach

1. Calculate total daily insulin requirement: 0.3-0.5 units/kg/day for most patients 2
2. Divide insulin regimen:
   • 50% as basal insulin (long-acting)
   • 50% as prandial insulin (if eating)
   • Add correctional insulin (sliding scale) based on pre-meal glucose 2
3. Monitor and adjust:
   • Check glucose before meals and at bedtime for eating patients
   • Every 4-6 hours for patients on continuous feeding or NPO 2
   • Adjust insulin doses based on patterns, not single readings

Special Considerations

• For patients with poor oral intake: Reduce total insulin to 0.1-0.15 units/kg/day, primarily as basal insulin 2
• For patients on enteral feeding: Consider diabetes-specific formulas with lower carbohydrate content 2
• If feeding is interrupted: Start 10% dextrose infusion at 50 mL/hr to prevent hypoglycemia 2

Conclusion

Sliding scale regular insulin has an important but limited role in hospital glycemic management. It should be used as a supplementary correction component of a comprehensive insulin regimen that includes basal insulin, rather than as the sole method of glycemic control.