When is sliding‑scale insulin appropriate, how should the correction dose be calculated (approximately 0.1 U/kg based on current blood glucose levels), and what monitoring and transition to basal‑bolus therapy are recommended?

Sliding‑Scale Insulin: When Appropriate, Dosing, and Transition Strategies

Sliding‑Scale Insulin Is Ineffective and Should Not Be Used as Monotherapy

Sliding‑scale insulin (SSI) as the sole insulin regimen is strongly condemned by all major diabetes guidelines and should be immediately discontinued in favor of scheduled basal‑bolus therapy. 1, 2, 3, 4, 5, 6

• SSI provides only reactive treatment—addressing hyperglycemia after it occurs—rather than preventing glucose excursions, resulting in dangerous glucose variability and poor clinical outcomes. 1, 5, 6
• Only ≈38 % of hospitalized patients on SSI alone achieve mean glucose < 140 mg/dL, compared with ≈68 % using scheduled basal‑bolus regimens, with no increase in hypoglycemia when basal‑bolus is correctly implemented. 1, 2, 6
• Meta‑analysis of 11 randomized trials (1,322 patients) demonstrates that SSI fails to improve glycemic control and significantly increases hyperglycemic episodes (mean glucose 27 mg/dL higher than comparator regimens). 4, 6
• Treatment failure (defined as > 2 consecutive glucose readings > 240 mg/dL) occurs in ≈19 % of SSI patients versus 0–2 % on basal‑bolus therapy. 1

Extremely Limited Circumstances Where SSI Alone May Be Acceptable

SSI as monotherapy is appropriate only in two narrow clinical scenarios:

• Patients without pre‑existing diabetes who develop mild stress hyperglycemia during hospitalization (e.g., glucose 140–180 mg/dL from acute illness or corticosteroids). 2, 3
• Well‑controlled type 2 diabetes patients (HbA1c < 7 %) managed by diet alone or minimal oral therapy at home who develop mild transient hyperglycemia during hospitalization. 2, 3

In all other situations—including any patient with established diabetes requiring insulin—SSI must never be used as the sole regimen. 1, 2, 3

Proper Role of Correction Insulin: Supplement to Scheduled Basal‑Bolus Therapy

Correction (sliding‑scale) doses are intended only as supplements to scheduled basal and prandial insulin, never as a replacement. 1, 2

Evidence‑Based Correction Dosing Protocol

• Add 2 units of rapid‑acting insulin for pre‑meal glucose > 250 mg/dL (13.9 mmol/L). 1
• Add 4 units for pre‑meal glucose > 350 mg/dL (19.4 mmol/L). 1
• These correction units are administered in addition to the scheduled prandial dose, not instead of it. 1

Individualized Correction Using Insulin Sensitivity Factor (ISF)

• Calculate ISF = 1500 ÷ total daily insulin dose (for regular insulin) or 1700 ÷ TDD (for rapid‑acting analogs). 1
• Correction dose = (Current glucose – Target glucose) ÷ ISF. 1
• Example: For a patient on 50 units/day total insulin with glucose 280 mg/dL and target 120 mg/dL, ISF = 1500 ÷ 50 = 30; correction = (280 – 120) ÷ 30 = 5.3 units (round to 5 units). 1

Critical Safety Considerations

• Never administer rapid‑acting insulin at bedtime as a sole correction dose, as this markedly increases nocturnal hypoglycemia risk. 1, 2
• Frequent need for correction doses signals inadequate scheduled insulin; increase basal or prandial components rather than relying on reactive corrections. 1, 2

Recommended Alternative: Basal‑Plus or Basal‑Bolus Regimens

Basal‑Plus Regimen (For Patients with Poor Oral Intake or NPO)

For hospitalized patients with limited oral intake, use basal insulin plus correction doses only:

• Start basal insulin (glargine, detemir, or degludec) at 0.1–0.25 units/kg/day once daily. 1, 2, 3
• Add correction doses of rapid‑acting insulin before meals (if eating) or every 4–6 hours (if NPO) using the protocol above. 1, 2
• Check glucose every 4–6 hours for NPO patients. 1, 2
• This approach is superior to SSI alone while minimizing hypoglycemia risk in vulnerable patients. 2, 3

Basal‑Bolus Regimen (For Patients Eating Regular Meals)

For non‑critically ill hospitalized patients with good nutritional intake:

• Calculate total daily insulin dose: 0.3–0.5 units/kg/day for insulin‑naive patients with moderate hyperglycemia. 1, 2
• Allocate 50 % as basal insulin once daily (e.g., glargine at bedtime). 1, 2
• Allocate 50 % as prandial insulin divided among three meals using rapid‑acting analogs (lispro, aspart, glulisine) given 0–15 minutes before meals. 1, 2
• Add correction doses per the protocol above. 1

Titration Protocols

Basal insulin titration:

• Increase by 2 units every 3 days if fasting glucose is 140–179 mg/dL. 1
• Increase by 4 units every 3 days if fasting glucose is ≥180 mg/dL. 1
• Target fasting glucose 80–130 mg/dL. 1

Prandial insulin titration:

• Adjust each meal dose by 1–2 units (≈10–15 %) every 3 days based on 2‑hour post‑prandial glucose. 1
• Target post‑prandial glucose < 180 mg/dL. 1

Monitoring Requirements

• Patients eating regular meals: Check glucose before each meal and at bedtime (minimum 4 times daily). 1, 2
• NPO or poor oral intake: Check glucose every 4–6 hours. 1, 2
• Daily fasting glucose is essential to guide basal insulin adjustments. 1
• 2‑hour post‑prandial glucose after each meal assesses prandial adequacy. 1

Transition from SSI to Basal‑Bolus Therapy

When a patient is currently on SSI alone with poor control (e.g., multiple readings > 180 mg/dL):

1. Discontinue SSI as the sole regimen immediately. 1, 2
2. Initiate basal insulin at 0.3–0.5 units/kg/day (50 % of total dose) once daily. 1, 2
3. Start prandial insulin at 4 units before each of the three largest meals (or 10 % of basal dose per meal). 1
4. Continue correction doses as adjunct using the 2‑unit/4‑unit protocol above. 1
5. Titrate every 3 days per protocols until targets achieved. 1

Common Pitfalls to Avoid

• Do not continue unchanged SSI regimens when glucose remains uncontrolled; this is the most frequent error in inpatient insulin management. 1, 2, 7
• Never use SSI as monotherapy in type 1 diabetes, as it can precipitate diabetic ketoacidosis. 1, 2
• Do not delay transition to scheduled insulin when glucose values repeatedly exceed 180 mg/dL; prolonged hyperglycemia increases complication risk. 1, 4, 5
• Avoid relying solely on correction doses without adjusting scheduled basal and prandial insulin, which perpetuates inadequate control. 1, 2
• Do not increase basal insulin beyond 0.5–1.0 units/kg/day without adding prandial coverage, to prevent over‑basalization and hypoglycemia. 1

Hypoglycemia Management

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

Special Populations Requiring Lower Doses

For high‑risk patients (age > 65 years, renal impairment, poor oral intake):

• Start with 0.1–0.25 units/kg/day total insulin to minimize hypoglycemia risk. 1, 2, 3
• For patients on ≥0.6 units/kg/day insulin at home, reduce total daily dose by 20 % upon hospitalization. 1, 2, 3

Expected Clinical Outcomes with Proper Basal‑Bolus Therapy

• ≈68 % of patients achieve mean glucose < 140 mg/dL versus ≈38 % on SSI alone. 1, 2, 6
• Basal‑bolus therapy does not increase hypoglycemia incidence compared with inadequate SSI approaches when correctly implemented. 1, 6
• Target glucose range for non‑critically ill hospitalized patients: 140–180 mg/dL. 1, 2