What is the recommended Lispro (insulin lispro) sliding scale for a patient with diabetes requiring insulin therapy?

Recommended Lispro Sliding Scale

For patients requiring correction insulin, use a simplified sliding scale approach: give 2 units of lispro for premeal glucose >250 mg/dL (13.9 mmol/L) and 4 units for premeal glucose >350 mg/dL (19.4 mmol/L), but this should only be used as a temporary adjunct while adjusting scheduled basal and prandial insulin—never as monotherapy. 1

Critical Context: Sliding Scale Insulin is Condemned as Monotherapy

Sliding scale insulin (SSI) as the sole treatment is explicitly condemned by all major diabetes guidelines and has been shown to be ineffective, treating hyperglycemia reactively after it occurs rather than preventing it. 2, 3 Studies demonstrate that SSI monotherapy results in:

• Only 6% of patients achieving good glycemic control through 5 days of therapy 3
• 84% of insulin injections producing subtherapeutic effects with persistently elevated glucose 3
• Poor glycemic control in 51-68% of patients on any given day 3
• Scheduled basal-bolus regimens achieving mean blood glucose <140 mg/dL in 68% of patients versus only 38% with SSI alone 2

Appropriate Use of Lispro Correction Doses

Simplified Correction Scale (Only as Adjunct to Scheduled Insulin)

While adjusting scheduled basal and prandial insulin regimens, the following simplified correction approach may be used temporarily 1:

• Premeal glucose >250 mg/dL (13.9 mmol/L): Give 2 units of lispro 1
• Premeal glucose >350 mg/dL (19.4 mmol/L): Give 4 units of lispro 1

Stop using this sliding scale when correction doses are not needed daily. 1

Individualized Correction Factor (Preferred Method)

For patients already on established insulin therapy, calculate an individualized insulin sensitivity factor (ISF) 2:

• Formula: ISF = 1500 ÷ Total Daily Dose (TDD) of insulin 2
• Correction dose: (Current glucose - Target glucose) ÷ ISF 2
• Target glucose: 90-150 mg/dL (5.0-8.3 mmol/L) before meals 1

Proper Insulin Regimen Structure

Foundation: Scheduled Basal-Bolus Therapy Required

All patients requiring insulin should be on a scheduled regimen with basal, prandial, and correction components—not correction insulin alone. 2

Initial dosing for hospitalized patients:

• Insulin-naive or low-dose insulin: 0.3-0.5 units/kg/day total daily dose, with half as basal insulin 2
• High-dose home insulin (≥0.6 units/kg/day): Reduce total daily dose by 20% to prevent hypoglycemia 2
• High-risk patients (elderly >65 years, renal failure, poor oral intake): Use lower doses of 0.1-0.25 units/kg/day 2

Prandial Lispro Dosing

Lispro should be administered 0-15 minutes before meals, preferably immediately before meals, for optimal postprandial glucose control. 4, 5, 6

Starting prandial dose:

• Begin with 4 units of lispro before the largest meal 2
• Alternatively, use 10% of the current basal insulin dose 2

Titration:

• Increase by 1-2 units or 10-15% every 3 days based on 2-hour postprandial glucose readings 2
• Target postprandial glucose <180 mg/dL 2

Advantages of Lispro Over Regular Insulin

Lispro provides superior postprandial glycemic control compared to regular human insulin, with a more rapid onset and shorter duration of action that better mimics physiological insulin secretion. 5, 6

• Pharmacokinetics: Maximum insulin concentrations are higher and reached earlier with lispro, with faster return to baseline 5
• Clinical outcomes: 1- and 2-hour postprandial glucose levels are similar to or lower than regular insulin 5
• Hypoglycemia: Lower incidence of night-time and severe hypoglycemic episodes compared to regular insulin 5
• Convenience: Can be administered immediately before or at the end of meals, versus 20-45 minutes before meals for regular insulin 7, 5

Common Pitfalls to Avoid

• Never rely on sliding scale insulin as monotherapy—this approach is ineffective and leads to dangerous glucose fluctuations 2, 3
• Never use rapid-acting insulin at bedtime—this increases nocturnal hypoglycemia risk 1
• Avoid "stacking" correction doses—insulin from the previous dose may still be active 2
• Do not delay scheduled insulin adjustments—75% of hospitalized patients who experienced hypoglycemia had no basal insulin dose adjustment before the next administration 2
• Never abruptly discontinue oral medications when starting insulin—continue metformin unless contraindicated 4

Monitoring Requirements

• Daily fasting blood glucose monitoring is essential during titration 2
• Check premeal and 2-hour postprandial glucose to guide prandial insulin adjustments 2
• Reassess adequacy of insulin dose at every clinical visit 2
• If hypoglycemia occurs without clear cause, reduce the dose by 10-20% immediately 2