What is the recommended sliding‑scale dosing protocol for Humalog (insulin lispro) in an adult inpatient with type 1 diabetes or insulin‑requiring type 2 diabetes?

Humalog Sliding Scale Dosing in Hospitalized Adults

Sliding‑scale insulin as monotherapy is strongly discouraged and should be discontinued immediately.

The American Diabetes Association explicitly condemns the use of sliding‑scale insulin (SSI) alone for hospitalized patients with established insulin requirements, stating it should be replaced with a scheduled basal‑bolus regimen. 1, 2 SSI treats hyperglycemia reactively—after it has already occurred—rather than preventing it, leading to dangerous glucose fluctuations that worsen both hyper‑ and hypoglycemia. 1

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Why Sliding‑Scale Monotherapy Fails

• Only ≈38 % of hospitalized patients on SSI alone achieve mean glucose < 140 mg/dL, compared with ≈68 % using a scheduled basal‑bolus regimen, with no increase in hypoglycemia when the basal‑bolus approach is properly implemented. 1, 2
• SSI regimens prescribed on admission are typically continued unchanged throughout hospitalization, even when glucose control remains poor. 1
• The reactive nature of SSI causes rapid glucose swings, exacerbating both hyperglycemia and hypoglycemia. 1

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Proper Role of Correction Insulin (Including Humalog)

Correction doses are adjuncts to scheduled insulin—never replacements. 1, 2

Simplified Correction Protocol

• Add 2 units of Humalog for pre‑meal glucose > 250 mg/dL (13.9 mmol/L). 2
• Add 4 units of Humalog for pre‑meal glucose > 350 mg/dL (19.4 mmol/L). 2
• These correction doses must be given in addition to scheduled basal and prandial insulin, not as a substitute. 1, 2

Individualized Correction Dosing

• Calculate an insulin sensitivity factor (ISF) = 1500 ÷ total daily insulin dose for regular insulin, or 1700 ÷ total daily insulin dose for rapid‑acting analogs like Humalog. 2
• Correction dose = (Current glucose – Target glucose) ÷ ISF. 2
• If correction doses are frequently required, the scheduled basal or prandial insulin doses should be increased accordingly—do not rely on repeated corrections. 1

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Recommended Basal‑Bolus Regimen Structure

Initial Dosing (Non‑Critically Ill Hospitalized Patients)

Standard‑risk patients (insulin‑naïve or low‑dose home therapy):

• Start with 0.3–0.5 U/kg/day total daily dose (TDD). 1, 2
• Allocate 50 % as basal insulin (glargine, detemir, or degludec) given once daily. 1, 2
• Allocate 50 % as prandial insulin (Humalog, aspart, or glulisine) divided equally among three meals. 1, 2

High‑risk patients (age > 65 yr, renal impairment, poor oral intake):

• Use a reduced starting dose of 0.1–0.25 U/kg/day to minimize hypoglycemia risk. 1, 2

Patients on high‑dose home insulin (≥0.6 U/kg/day):

• Reduce the admission TDD by ≈20 % to prevent inpatient hypoglycemia. 1, 2

Timing of Humalog Administration

• Administer Humalog 0–15 minutes before meals (ideally immediately before eating) for optimal post‑prandial glucose control. 1, 2, 3
• Never give Humalog at bedtime as a sole correction dose, as this markedly raises the risk of nocturnal hypoglycemia. 1, 2

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Titration Protocols

Basal Insulin Titration

• Increase basal dose by 2 U every 3 days if fasting glucose is 140–179 mg/dL. 1, 2
• Increase basal dose by 4 U every 3 days if fasting glucose is ≥180 mg/dL. 1, 2
• Target fasting glucose 80–130 mg/dL. 1, 2
• When basal insulin reaches 0.5–1.0 U/kg/day without achieving targets, add or intensify prandial insulin rather than further basal escalation. 1, 2

Prandial Humalog Titration

• Start with 4 U before each of the three largest meals, or use ≈10 % of the current basal dose. 1, 2
• Increase each meal dose by 1–2 U (≈10–15 %) every 3 days based on the 2‑hour post‑prandial glucose reading. 1, 2
• Target post‑prandial glucose < 180 mg/dL. 1, 2

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Glucose Monitoring Protocol

Patients eating regular meals:

• Check glucose before each meal and at bedtime (minimum 4 times daily). 1, 2

Patients with poor oral intake or NPO:

• Check glucose every 4–6 hours. 1, 2
• Use a basal‑plus‑correction regimen (basal insulin plus correction doses only) rather than scheduled prandial insulin. 1, 4

Guiding adjustments:

• Use daily fasting glucose to guide basal insulin titration. 1, 2
• Obtain 2‑hour post‑prandial glucose after each meal to assess prandial adequacy. 1, 2

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Hypoglycemia Management

• Treat glucose < 70 mg/dL promptly with ≈15 g of fast‑acting carbohydrate, recheck in 15 minutes, and repeat if needed. 1, 2
• If hypoglycemia occurs without an obvious cause, reduce the implicated insulin dose by 10–20 % immediately. 1, 2
• Document every hypoglycemic episode in the medical record for quality‑tracking purposes. 1

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Limited Acceptable Uses of Sliding‑Scale Insulin Alone

SSI as monotherapy may be appropriate only in the following narrow circumstances:

• Patients without pre‑existing diabetes who develop mild stress hyperglycemia during hospitalization. 1, 4
• Patients with well‑controlled type 2 diabetes (HbA1c < 7 %) on diet alone or minimal oral therapy at home who have mild hyperglycemia during hospitalization. 1, 4
• Patients who are NPO with no nutritional replacement and only mild hyperglycemia. 1
• Patients who are new to steroids or tapering steroids. 1

In all other cases, SSI alone is inadequate and unsafe. 1, 2

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Common Pitfalls to Avoid

• Do not use SSI as monotherapy in patients with type 1 diabetes or established insulin requirements—this can precipitate diabetic ketoacidosis. 1, 2
• Do not delay transition to a scheduled basal‑bolus regimen when glucose values repeatedly exceed 180 mg/dL. 1, 2
• Do not rely solely on correction doses without adjusting scheduled basal and prandial insulin when corrections are frequently needed. 1, 2
• Do not give Humalog at bedtime as a sole correction dose—this significantly increases nocturnal hypoglycemia risk. 1, 2
• Do not continue SSI unchanged throughout hospitalization when glucose control remains poor. 1

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Expected Clinical Outcomes

• With properly implemented basal‑bolus therapy using Humalog, ≈68 % of patients achieve mean glucose < 140 mg/dL versus ≈38 % with SSI alone. 1, 2
• Correctly executed basal‑bolus regimens do not increase overall hypoglycemia incidence compared with inadequate SSI approaches. 1, 2
• The recommended target glucose range for non‑critically ill hospitalized patients is 140–180 mg/dL. 1, 2

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Implementation Algorithm (Key Steps)

1. Discontinue SSI as monotherapy immediately. 1, 2
2. Start basal insulin (glargine, detemir, or degludec) at 0.3–0.5 U/kg/day (50 % of TDD) for standard‑risk patients. 1, 2
3. Start prandial Humalog at 4 U before each meal (remaining 50 % of TDD). 1, 2
4. Add correction doses (2 U for glucose > 250 mg/dL; 4 U for > 350 mg/dL) as supplements only. 1, 2
5. Titrate basal insulin every 3 days based on fasting glucose. 1, 2
6. Titrate prandial Humalog every 3 days based on 2‑hour post‑prandial glucose. 1, 2
7. Monitor glucose before each meal and at bedtime (or every 4–6 hours if NPO). 1, 2