What is the approach for managing hyperglycemia with sliding scale insulin lispro (Humalog)?

Sliding Scale Insulin Lispro: Avoid as Monotherapy in Hospitalized Patients with Diabetes

Sliding scale insulin lispro (Humalog) alone should not be used as the primary approach for managing hyperglycemia in hospitalized patients with type 2 diabetes, as it is associated with clinically significant hyperglycemia and has been condemned in clinical guidelines. 1

Why Sliding Scale Insulin Alone is Inadequate

• Sliding scale insulin is a reactive approach that treats hyperglycemia only after it has already occurred, rather than preventing it proactively. 1
• Clinical guidelines explicitly discourage its use in hospitalized patients with established diabetes due to poor glycemic control outcomes. 1
• Randomized trials consistently demonstrate superior glycemic control with basal-bolus regimens compared to sliding scale insulin alone in type 2 diabetes patients. 1
• The basal-bolus approach reduces complications including postoperative wound infection, pneumonia, bacteremia, and acute renal and respiratory failure compared to sliding scale insulin. 1

When Sliding Scale Insulin May Be Appropriate

Limited exceptions exist where sliding scale insulin lispro alone might be acceptable:

• Patients without diabetes who have mild stress hyperglycemia may be managed with sliding scale insulin alone. 1
• Never use sliding scale insulin alone in type 1 diabetes patients, as this can lead to dangerous hyperglycemia and ketoacidosis. 1

The Preferred Approach: Basal-Bolus Regimen

For hospitalized patients with type 2 diabetes requiring insulin, use a basal-bolus regimen:

Initial Dosing Strategy

• Start with 0.3-0.5 units/kg/day total daily insulin dose for insulin-naive patients or those on low-dose insulin at home. 1
• Divide the total daily dose equally: 50% as basal insulin (given once or twice daily) and 50% as rapid-acting insulin lispro (divided before three meals). 1
• For patients at higher risk of hypoglycemia (age >65 years, renal failure, poor oral intake), use the lower end of the dosing range (0.3 units/kg/day). 1

Incorporating Correctional Insulin

• Add correctional (sliding scale) doses of insulin lispro on top of the scheduled basal-bolus regimen to address unexpected hyperglycemic excursions. 1
• This uses lispro as a supplement, not as monotherapy, which is the key distinction from the discouraged sliding scale-only approach. 1

Timing of Lispro Administration

• Administer insulin lispro immediately before meals (within 15 minutes) or right after eating. 1, 2
• In hyperglycemic patients (glucose >10.2 mmol/L or 184 mg/dL), consider giving lispro 15 minutes before the meal to optimize postprandial glucose control. 3
• Lispro provides better postprandial glucose control than regular human insulin due to its faster onset and shorter duration of action. 1, 4

Alternative for Mild Hyperglycemia

For patients with mild hyperglycemia (blood glucose <11.1 mmol/L or 200 mg/dL):

• Consider a basal-plus regimen consisting of basal insulin (0.1-0.25 units/kg/day) plus correctional doses of lispro for elevated glucose readings. 1
• This approach reduces the risk of iatrogenic hypoglycemia compared to full basal-bolus regimens while providing better control than sliding scale alone. 1

Critical Pitfalls to Avoid

• Do not rely on sliding scale insulin lispro as the sole insulin therapy in patients with established diabetes, as this leads to poor glycemic control. 1
• Recognize that lispro's short duration of action (approximately 4 hours) means it does not provide adequate basal insulin coverage between meals and overnight. 1, 2
• Be aware that using lispro alone can cause nocturnal hyperglycemia due to lack of basal insulin coverage, particularly in patients on premeal-only insulin regimens. 5
• Monitor for hypoglycemia risk when transitioning from sliding scale to basal-bolus regimens, with incidence of mild hypoglycemia ranging from 12-30% in controlled settings. 1

Practical Implementation

• Ensure proper patient education regarding glucose monitoring, insulin injection technique, recognition and treatment of hypoglycemia, and sick day rules. 1
• Use lispro within 15 minutes before eating or right after meals for optimal postprandial glucose control. 2
• Do not mix lispro with any other insulin when used in insulin pumps, though it can be mixed with NPH insulin when using syringe injections. 2