How to Dose Insulin Lispro

Administer insulin lispro 0–15 minutes before meals as prandial (mealtime) insulin, starting with 4 units per meal or 10% of your basal insulin dose, and titrate by 1–2 units every 3 days based on 2-hour postprandial glucose readings until you reach a target of <180 mg/dL. 1

Initial Dosing Strategy

For Type 1 Diabetes

Start with a total daily insulin dose of 0.5 units/kg/day, dividing it so that 50% is basal insulin (long-acting) and 50% is prandial insulin (lispro) split among three meals 2
For a metabolically stable adult, this translates to approximately 4–5 units of lispro before each meal 2
Patients presenting with ketoacidosis or during the honeymoon phase may require higher (0.6–1.0 units/kg/day) or lower (0.2–0.6 units/kg/day) doses, respectively 2

For Type 2 Diabetes

Add lispro when basal insulin alone fails to achieve glycemic targets after 3–6 months of optimization, or when basal insulin exceeds 0.5 units/kg/day 1
Start with 4 units of lispro before the largest meal or use 10% of the current basal insulin dose 1
For severe hyperglycemia (HbA1c ≥9% or glucose ≥300 mg/dL), consider starting basal-bolus therapy immediately with 0.3–0.5 units/kg/day total, split 50% basal and 50% prandial 1

Timing of Administration

Inject lispro 0–15 minutes before meals—ideally immediately before eating—to optimize postprandial glucose control. 1, 3

Lispro has a rapid onset (5 minutes), peak action at 1–2 hours, and duration of 3–4 hours 4, 3
This faster pharmacokinetic profile allows injection closer to mealtime compared to regular human insulin (which requires 30–45 minutes pre-meal) 3, 5

Special Situation: Pre-Existing Hyperglycemia

If fasting or pre-meal glucose is >250 mg/dL, inject lispro 15–30 minutes before the meal to improve postprandial excursion 6
Injecting 15 minutes early in hyperglycemic patients significantly reduces postprandial glucose rise compared to injecting at mealtime 6
Avoid injecting 30 minutes early unless closely monitored, as this can cause late postprandial hypoglycemia in some patients 6

Titration Protocol

Prandial Lispro Adjustment

Increase each meal dose by 1–2 units (or 10–15%) every 3 days based on the 2-hour postprandial glucose reading 1
Target postprandial glucose <180 mg/dL 1
If hypoglycemia occurs without a clear cause, reduce the implicated dose by 10–20% immediately 1

Carbohydrate-Based Dosing (Advanced)

Calculate an insulin-to-carbohydrate ratio (ICR) using the formula: 450 ÷ total daily insulin dose 1
For example, if total daily dose is 45 units, ICR = 450 ÷ 45 = 1 unit per 10 grams of carbohydrate 1
Adjust the ICR if postprandial glucose consistently misses target 1

Correction (Supplemental) Dosing

Add correction insulin on top of scheduled prandial doses when pre-meal glucose exceeds target.

Use a simplified sliding scale: add 2 units for glucose >250 mg/dL and 4 units for glucose >350 mg/dL 1
For individualized correction, calculate an insulin sensitivity factor (ISF): 1500 ÷ total daily insulin dose 1
Correction dose = (Current glucose – Target glucose) ÷ ISF 1
Never use correction insulin as monotherapy—it must supplement a scheduled basal-bolus regimen 1

Monitoring Requirements

Check fasting glucose daily during titration to guide basal insulin adjustments 1
Check pre-meal glucose immediately before each meal to calculate correction doses 1
Check 2-hour postprandial glucose to assess adequacy of prandial lispro and guide titration 1
Reassess HbA1c every 3 months during intensive titration 1

Critical Thresholds and Safety Limits

When to Stop Escalating Basal Insulin

When basal insulin approaches 0.5–1.0 units/kg/day without achieving glycemic targets, add or intensify prandial lispro rather than continuing to escalate basal insulin alone 1
Signs of "overbasalization" include: basal dose >0.5 units/kg/day, bedtime-to-morning glucose drop ≥50 mg/dL, hypoglycemia, and high glucose variability 1

Hypoglycemia Management

Treat any glucose <70 mg/dL immediately with 15 grams of fast-acting carbohydrate, recheck in 15 minutes, and repeat if needed 1
Never give lispro at bedtime as a sole correction dose—this markedly increases nocturnal hypoglycemia risk 1

Special Populations and Situations

Hospitalized Patients

For non-critically ill inpatients eating regular meals, use 0.3–0.5 units/kg/day total insulin (50% basal, 50% prandial divided among three meals) 1
For high-risk patients (age >65, renal impairment, poor oral intake), start with 0.1–0.25 units/kg/day 1
Check glucose before each meal and at bedtime; for NPO patients, check every 4–6 hours 1

Renal or Hepatic Impairment

Insulin requirements may be reduced in renal or hepatic impairment 7
For CKD Stage 5, reduce total daily insulin by 50% in type 2 diabetes and 35–40% in type 1 diabetes 2
Titrate conservatively and monitor closely for hypoglycemia 2

Continuous Tube Feeding

For patients on continuous enteral nutrition, calculate insulin needs at approximately 1 unit per 10–15 grams of carbohydrate in the formula 1
Use NPH every 12 hours or regular insulin every 6 hours to cover the continuous nutritional load, rather than lispro 1

Glucocorticoid Therapy

Steroid use may require 40–60% increases in prandial and correction insulin in addition to basal insulin 1
Insulin requirements can be extraordinary and highly variable during acute illness 4

Concentrated Formulations for High-Dose Requirements

U-200 lispro (200 units/mL) is available for patients requiring large insulin doses 4
U-200 has identical pharmacokinetics to U-100 but allows half the injection volume 4
Available only in prefilled pens to minimize dosing errors 1
Consider U-200 when total daily lispro exceeds 60–80 units to improve comfort and adherence 4

Combination Therapy Considerations

Continue Metformin

Always continue metformin at maximum tolerated dose (up to 2,000–2,550 mg/day) when adding lispro, unless contraindicated 1
Metformin reduces total insulin requirements by 20–30% and provides superior glycemic control 1

Discontinue Sulfonylureas

Stop sulfonylureas when initiating basal-bolus insulin to prevent additive hypoglycemia risk 1

Alternative to Prandial Insulin

Consider adding a GLP-1 receptor agonist instead of lispro when basal insulin exceeds 0.5 units/kg/day 1
GLP-1 agonists address postprandial hyperglycemia with less hypoglycemia and weight gain compared to prandial insulin 1

Common Pitfalls to Avoid

Do not use sliding-scale insulin as monotherapy—major diabetes guidelines condemn this approach as ineffective and unsafe 1
Do not delay adding prandial insulin when basal insulin exceeds 0.5 units/kg/day without achieving targets 1
Do not give lispro at bedtime as a sole correction dose—this markedly raises nocturnal hypoglycemia risk 1
Do not discontinue metformin when starting insulin unless contraindicated—this leads to higher insulin requirements and more weight gain 1
Do not inject lispro 30–45 minutes before meals like regular insulin—its rapid onset makes this unnecessary and increases hypoglycemia risk 3, 5
Do not rely solely on correction doses without adjusting scheduled basal and prandial insulin—this perpetuates inadequate control 1

Expected Clinical Outcomes

With properly implemented basal-bolus therapy using lispro, 68% of patients achieve mean glucose <140 mg/dL versus only 38% with sliding-scale insulin alone 1
Expect HbA1c reduction of 2–3% (or 3–4% in severe hyperglycemia) over 3–6 months with intensive titration 1
Lispro provides better postprandial glucose control and lower rates of nocturnal hypoglycemia compared to regular human insulin 3, 5
No increase in overall hypoglycemia incidence when basal-bolus regimens are correctly implemented versus inadequate sliding-scale approaches 1

How should insulin lispro be dosed?

Help us tailor your experience