Additional Insulin Lispro Dosing After 22-Unit Sliding Scale
After administering 22 units of insulin lispro on a sliding scale, no additional correction dose should be given at that time—instead, reassess blood glucose in 1-2 hours when lispro peaks, and only then consider further correction if hyperglycemia persists. 1
Immediate Management
The 22-unit dose already represents a substantial correction for severe hyperglycemia. Adding more insulin immediately risks:
- Insulin stacking, where overlapping insulin action causes severe hypoglycemia 1, 2
- Peak action occurs 1-2 hours post-injection for rapid-acting insulin lispro, meaning the full effect hasn't yet manifested 3, 4
When to Consider Additional Insulin
If reassessing 2-4 hours after the initial dose:
- For glucose >250 mg/dL but <350 mg/dL: Give 2 units of insulin lispro 1, 2
- For glucose >350 mg/dL: Give 4 units of insulin lispro 1, 2
These simplified sliding scale recommendations from the American Diabetes Association are intended for temporary use only while adjusting the underlying insulin regimen. 1
Critical Action: Fix the Underlying Problem
A 22-unit correction dose signals that the basal insulin regimen is inadequate. 2, 3
The need for such large correction doses daily indicates you should:
- Increase basal insulin by 2 units every 3-7 days until fasting glucose reaches 90-150 mg/dL 2, 3
- Stop using sliding scale when not needed daily—this approach should only be temporary 1, 2
- Consider that 50-70% of total daily insulin should be basal in most patients 1
Safety Monitoring
Monitor for hypoglycemia 1-2 hours post-injection when lispro action peaks, particularly in patients with: 2, 3
- Impaired renal function (insulin clearance is reduced) 2
- Concurrent sulfonylurea use (additive hypoglycemia risk) 2
- Older adults or those with cognitive impairment 1
Never administer rapid-acting insulin at bedtime due to nocturnal hypoglycemia risk. 1, 3
Timing Considerations for Future Doses
For hyperglycemic patients (glucose >180 mg/dL), inject lispro 15 minutes before the meal rather than immediately before eating, as this timing improves postprandial glucose control. 5 However, injecting 30 minutes before meals may cause late hypoglycemia in some patients. 5
Common Pitfalls to Avoid
- Giving correction insulin too frequently (more often than every 4 hours for lispro) leads to insulin stacking 1, 2
- Failing to address inadequate basal insulin when correction doses are needed daily 2, 3
- Using sliding scales as a long-term strategy rather than a temporary bridge while optimizing the regimen 1, 2
- Not accounting for lispro's 3-4 hour duration of action when calculating subsequent doses 3, 4