How should rapid‑acting bolus insulin be titrated in a 70‑kg insulin‑naïve adult with type 1 or type 2 diabetes starting a basal‑bolus regimen using pre‑meal and post‑prandial glucose values?

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Last updated: February 16, 2026 • View editorial policy

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Titrating Bolus Insulin Based on Pre‑Meal and Post‑Prandial Glucose Values

For a 70‑kg insulin‑naïve adult starting a basal‑bolus regimen, begin with 4 units of rapid‑acting insulin before each of the three largest meals (or 10 % of the basal dose), then increase each meal dose by 1–2 units every 3 days based on the 2‑hour post‑prandial glucose reading, targeting post‑prandial glucose < 180 mg/dL. 1

Initial Prandial Insulin Dosing

  • Start with 4 units of rapid‑acting insulin (lispro, aspart, or glulisine) before each of the three main meals, or use 10 % of the current basal insulin dose as the initial prandial dose. 1
  • For a 70‑kg adult on a standard basal‑bolus regimen, the total daily insulin dose is typically 0.5 units/kg/day (≈ 35 units), with 50 % allocated to basal insulin (≈ 17–18 units once daily) and 50 % to prandial insulin (≈ 17–18 units total, or ≈ 6 units per meal). 1, 2
  • Administer rapid‑acting insulin 0–15 minutes before meals—ideally immediately before eating—to achieve optimal post‑prandial glucose control. 1, 3

Titration Protocol Based on Post‑Prandial Glucose

Step 1: Measure 2‑Hour Post‑Prandial Glucose

  • Check capillary glucose 2 hours after the start of each meal to assess the adequacy of that meal's prandial insulin dose. 1
  • The target 2‑hour post‑prandial glucose is < 180 mg/dL. 1, 4

Step 2: Adjust Each Meal Dose Independently

  • If post‑prandial glucose is consistently > 180 mg/dL, increase the prandial insulin dose for that specific meal by 1–2 units (or 10–15 %) every 3 days. 1, 2
  • If post‑prandial glucose is consistently 70–100 mg/dL, the dose is appropriate; no adjustment is needed. 1
  • If post‑prandial glucose is < 70 mg/dL, reduce the prandial insulin dose for that meal by 10–20 % immediately to prevent recurrent hypoglycemia. 1

Step 3: Titrate Each Meal Separately

  • Breakfast, lunch, and dinner prandial doses are adjusted independently based on their respective 2‑hour post‑prandial glucose readings. 1, 2
  • For example, if the 2‑hour post‑breakfast glucose is 220 mg/dL but the 2‑hour post‑lunch glucose is 140 mg/dL, increase only the breakfast prandial dose by 1–2 units; leave the lunch dose unchanged. 1

Using Pre‑Meal Glucose for Correction Doses

Correction Insulin Protocol

  • Pre‑meal glucose > 250 mg/dL: add 2 units of rapid‑acting insulin to the scheduled prandial dose. 1
  • Pre‑meal glucose > 350 mg/dL: add 4 units of rapid‑acting insulin to the scheduled prandial dose. 1
  • Correction doses are given in addition to the scheduled prandial insulin, not as a replacement. 1

Individualized Correction Factor (Insulin Sensitivity Factor)

  • Calculate the insulin sensitivity factor (ISF) as 1500 ÷ total daily insulin dose for regular insulin, or 1700 ÷ total daily insulin dose for rapid‑acting analogs. 1
  • Correction dose = (Current glucose – Target glucose) ÷ ISF. 1
  • For a 70‑kg adult on 35 units/day total insulin, ISF ≈ 1500 ÷ 35 ≈ 43 mg/dL per unit; if pre‑meal glucose is 250 mg/dL and target is 120 mg/dL, correction dose = (250 – 120) ÷ 43 ≈ 3 units. 1

Carbohydrate‑to‑Insulin Ratio (CIR) for Meal Coverage

  • Calculate the CIR as 450 ÷ total daily insulin dose for rapid‑acting analogs (or 500 ÷ total daily insulin dose for regular insulin). 1
  • For a 70‑kg adult on 35 units/day, CIR ≈ 450 ÷ 35 ≈ 13 grams of carbohydrate per unit of insulin. 1
  • If a meal contains 60 grams of carbohydrate, the prandial dose = 60 ÷ 13 ≈ 5 units. 1
  • Adjust the CIR if post‑prandial glucose consistently misses the target despite correct carbohydrate counting. 1

Monitoring Frequency and Targets

  • Fasting glucose: check daily to guide basal insulin titration; target 80–130 mg/dL. 1
  • Pre‑meal glucose: check immediately before each meal to calculate correction doses; target 90–150 mg/dL. 1
  • 2‑hour post‑prandial glucose: check after each meal to assess prandial insulin adequacy; target < 180 mg/dL. 1, 4
  • Bedtime glucose: check nightly to evaluate overall daily pattern and detect nocturnal hypoglycemia risk. 1

Stepwise Intensification Strategy

Starting with One Prandial Dose

  • If basal insulin alone is insufficient (fasting glucose 80–130 mg/dL but HbA1c remains above goal after 3–6 months), add a single prandial dose of 4 units before the largest meal or the meal causing the greatest post‑prandial glucose excursion. 1, 2, 4
  • Titrate this single prandial dose by 1–2 units every 3 days based on the 2‑hour post‑prandial glucose. 1, 2

Progressing to Two or Three Prandial Doses

  • If post‑prandial glucose remains > 180 mg/dL after other meals despite optimized basal insulin, add a second prandial dose (4 units) before the next meal with the highest post‑prandial excursion. 2, 4
  • Continue this stepwise approach until prandial insulin is given before all three main meals. 2, 4

Critical Threshold: Avoiding Over‑Basalization

  • When basal insulin approaches 0.5–1.0 units/kg/day (≈ 35–70 units for a 70‑kg adult) without achieving glycemic targets, add or intensify prandial insulin rather than further increasing basal insulin. 1, 2
  • Clinical signs of over‑basalization include:
    • Basal dose > 0.5 units/kg/day
    • Bedtime‑to‑morning glucose differential ≥ 50 mg/dL
    • Recurrent hypoglycemia
    • 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
  • If hypoglycemia occurs without an obvious cause (e.g., missed meal, excessive exercise), reduce the implicated prandial insulin dose by 10–20 % immediately. 1
  • Never administer rapid‑acting insulin at bedtime as a sole correction dose, as this markedly raises nocturnal hypoglycemia risk. 1

Timing Considerations for Optimal Post‑Prandial Control

  • Administering rapid‑acting insulin 20 minutes before a meal results in significantly lower 1‑ and 2‑hour post‑prandial glucose levels compared with dosing immediately before or 20 minutes after meal initiation. 5
  • However, the standard recommendation remains 0–15 minutes before meals to balance efficacy with practical adherence. 1, 3

Common Pitfalls to Avoid

  • Do not rely solely on correction insulin without adjusting scheduled prandial doses; frequent need for correction doses signals that the scheduled insulin is insufficient. 1
  • Do not use sliding‑scale insulin as monotherapy; correction doses must supplement a scheduled basal‑bolus regimen. 1
  • Do not delay adding prandial insulin when basal insulin exceeds 0.5 units/kg/day without achieving targets; this leads to over‑basalization and increased hypoglycemia risk. 1, 2
  • Do not adjust prandial insulin based on fasting glucose; fasting glucose reflects basal insulin adequacy, not meal coverage. 1

Expected Clinical Outcomes

  • With properly implemented basal‑bolus therapy, ≈ 68 % of patients achieve mean glucose < 140 mg/dL, compared with ≈ 38 % on sliding‑scale insulin alone. 1
  • HbA1c reductions of 2–3 % (or 3–4 % in severe hyperglycemia) are observed over 3–6 months with intensive titration. 1
  • Correctly executed basal‑bolus regimens do not increase overall hypoglycemia incidence compared with inadequate sliding‑scale approaches. 1

References

1
Guideline

Initial Dosing for Lantus (Insulin Glargine) in Patients Requiring Insulin Therapy

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2026

2
Guideline

Basal-Bolus Insulin Preparation

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2025

3
Research

EADSG Guidelines: Insulin Therapy in Diabetes.

Diabetes therapy : research, treatment and education of diabetes and related disorders, 2018

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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