What sliding‑scale insulin correction regimen should be used for an adult (≥18 years) with type 1 or type 2 diabetes, without severe renal or hepatic failure, who is hospitalized and unable to follow a scheduled insulin regimen?

Sliding‑Scale Insulin Should Be Abandoned in Hospitalized Adults with Diabetes

Sliding‑scale insulin as monotherapy is explicitly condemned by the American Diabetes Association and all major diabetes guideline societies; it must be replaced immediately with a scheduled basal‑bolus insulin regimen for any hospitalized adult (≥18 years) with type 1 or type 2 diabetes who requires insulin therapy. 1, 2

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Why Sliding‑Scale Insulin Fails

• Only ≈38 % of hospitalized patients managed with sliding‑scale insulin alone achieve a mean glucose < 140 mg/dL, versus ≈68 % with a scheduled basal‑bolus regimen—demonstrating clear inferiority. 1, 2, 3
• Sliding‑scale insulin reacts to hyperglycemia after it occurs rather than preventing it, creating dangerous glucose fluctuations that worsen both hyper‑ and hypoglycemia. 1, 2, 4
• Meta‑analysis of randomized controlled trials shows that sliding‑scale insulin provides no benefit in blood glucose control but is associated with a significantly higher incidence of hyperglycemic events (mean blood glucose 27 mg/dL higher than non‑sliding‑scale regimens). 5
• In real‑world practice, sliding‑scale insulin orders are often left unchanged throughout hospitalization despite persistent poor control, with approximately 30 % of anticipated insulin administrations having missing or uncertain documentation of execution, timing, glucose levels, or dose. 6
• Treatment failure (defined as > 2 consecutive glucose readings > 240 mg/dL) occurs in ≈19 % of patients on sliding‑scale alone versus 0–2 % on basal‑bolus therapy. 2

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The Correct Regimen: Scheduled Basal‑Bolus Insulin

For Patients Eating Regular Meals

Initiate a basal‑prandial‑correction insulin regimen immediately:

• Basal insulin (glargine, detemir, or degludec) given once daily provides continuous background coverage and suppresses hepatic glucose production independent of food intake. 1, 2
• Prandial insulin (rapid‑acting analogs: lispro, aspart, or glulisine) administered 0–15 minutes before each meal covers meal‑related glucose excursions. 1, 2
• Correction insulin is used only as a supplement to scheduled doses when pre‑meal glucose exceeds predefined thresholds (e.g., 2 units for > 250 mg/dL, 4 units for > 350 mg/dL)—it is not a replacement for scheduled insulin. 1, 2

Initial dosing:

• Standard‑risk patients (insulin‑naïve or low‑dose home therapy): start with a total daily dose of 0.3–0.5 U/kg/day, allocating 50 % to basal (once daily) and 50 % to prandial (divided among three meals). 1, 2
• High‑risk patients (age > 65 years, renal impairment, poor oral intake): use a lower 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 total daily dose by 20 % upon admission to prevent inpatient hypoglycemia. 1, 2

Titration protocol:

• Basal insulin: increase by 2 U every 3 days if fasting glucose is 140–179 mg/dL; increase by 4 U every 3 days if fasting glucose ≥ 180 mg/dL. Target fasting glucose 80–130 mg/dL. 1, 7
• Prandial insulin: increase each meal dose by 1–2 U (≈10–15 %) every 3 days based on 2‑hour post‑prandial glucose. Target post‑prandial glucose < 180 mg/dL. 1, 7
• If hypoglycemia (glucose < 70 mg/dL) occurs without an obvious cause, reduce the implicated insulin dose by 10–20 % immediately. 1, 7

For Patients with Poor Oral Intake or NPO

Use a basal‑plus‑correction regimen:

• Administer basal insulin once daily at a reduced dose (approximately 0.1–0.25 U/kg/day for high‑risk patients) to suppress hepatic glucose production even in the absence of food intake. 1, 2
• Add correction doses of rapid‑acting insulin only when point‑of‑care glucose exceeds predefined thresholds (e.g., 2 units for > 250 mg/dL, 4 units for > 350 mg/dL). 1, 2
• Never completely withhold basal insulin in patients with type 1 diabetes or insulin‑dependent type 2 diabetes, even when NPO, to prevent diabetic ketoacidosis. 1, 7
• Check glucose every 4–6 hours for NPO patients. 1

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Monitoring Requirements

• Patients eating regular meals: check capillary glucose before each meal and at bedtime (minimum 4 times daily). 1, 2
• Patients with poor intake or NPO: check glucose every 4–6 hours. 1, 2
• Daily fasting glucose is essential during titration to guide basal‑insulin adjustments. 1, 7
• Obtain 2‑hour post‑prandial glucose after each meal to assess prandial adequacy. 1, 7

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Target Glucose Ranges

• For non‑critically ill hospitalized patients, the target glucose range is 140–180 mg/dL. 1, 3
• More stringent targets of 110–140 mg/dL may be appropriate for selected patients if they can be achieved without significant hypoglycemia. 1
• Target fasting glucose 80–130 mg/dL and post‑prandial glucose < 180 mg/dL. 1, 7

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Hypoglycemia Management

• Treat any glucose < 70 mg/dL immediately with 15 g of fast‑acting carbohydrate, recheck in 15 minutes, and repeat if needed. 1, 7
• If hypoglycemia occurs without an obvious precipitant, reduce the implicated insulin dose by 10–20 % before the next administration. 1, 7
• Document every hypoglycemic episode in the medical record and track it for quality‑improvement purposes. 1
• Studies show that 75 % of hospitalized patients who experience hypoglycemia receive no basal insulin dose adjustment before the next dose—highlighting a critical management gap that must be addressed. 7

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Critical Pitfalls to Avoid

• Never use sliding‑scale insulin as monotherapy in hospitalized patients; this approach is condemned by all major diabetes guideline societies as ineffective and unsafe. 1, 2, 4, 5
• Never give rapid‑acting insulin at bedtime as a sole correction dose, as this markedly increases the risk of nocturnal hypoglycemia. 1, 7
• Do not delay adding prandial insulin when basal insulin alone fails to achieve target fasting glucose or when basal insulin approaches 0.5–1.0 U/kg/day without achieving glycemic goals. 1, 7
• Do not continue escalating basal insulin beyond 0.5–1.0 U/kg/day without addressing post‑prandial hyperglycemia, as this leads to "over‑basalization" with increased hypoglycemia risk and suboptimal control. 1, 7
• Do not rely solely on correction doses without adjusting scheduled basal and prandial insulin; correction insulin must supplement, not replace, scheduled insulin. 1, 2
• Never use sliding‑scale insulin as the sole treatment in type 1 diabetes, as it can precipitate diabetic ketoacidosis. 1, 7

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Expected Clinical Outcomes

• With properly implemented basal‑bolus therapy, ≈68 % of hospitalized patients achieve mean glucose < 140 mg/dL, compared with ≈38 % on sliding‑scale alone. 1, 2, 3
• Basal‑bolus therapy does not increase hypoglycemia incidence when correctly applied versus sliding‑scale monotherapy. 1, 2, 3
• Randomized controlled trials in general‑surgery patients with type 2 diabetes show that basal‑bolus therapy improves overall glycemic control and reduces hospital complications compared with sliding‑scale insulin. 2, 3

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Special Considerations

Transition from IV Insulin

• When discontinuing IV insulin, give subcutaneous basal insulin 2–4 hours before stopping the IV infusion to prevent rebound hyperglycemia and recurrent ketoacidosis. 1
• Convert to basal insulin at 60–80 % of the total daily IV infusion dose (or calculate as ½ of the 24‑hour IV insulin amount), split 50 % basal and 50 % prandial. 1, 7

Perioperative Management

• On the morning of surgery, administer 50 % of the usual NPH dose or 75–80 % of the usual long‑acting analog dose to reduce hypoglycemia risk while maintaining target glucose. 1
• While NPO perioperatively, monitor glucose every 2–4 hours and supplement with short‑ or rapid‑acting insulin as needed. 1
• Aim for a perioperative glucose range of 80–180 mg/dL. 1

Critically Ill Patients

• In the critical care setting, continuous intravenous insulin infusion is the most effective method for achieving glycemic targets, with a target glucose range of 140–180 mg/dL for the majority of critically ill patients. 1, 2, 3
• Initiate insulin therapy when glucose persistently exceeds 180 mg/dL. 1

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Summary Algorithm

1. Discontinue sliding‑scale insulin as monotherapy immediately. 1, 2
2. Initiate scheduled basal‑bolus insulin:
   • Basal insulin (glargine, detemir, or degludec) once daily. 1, 2
   • Prandial insulin (lispro, aspart, or glulisine) 0–15 minutes before each meal. 1, 2
   • Correction insulin as a supplement to scheduled doses. 1, 2
3. Titrate every 3 days based on fasting and post‑prandial glucose values. 1, 7
4. Monitor glucose before each meal and at bedtime (or every 4–6 hours if NPO). 1, 2
5. Treat hypoglycemia promptly and reduce the implicated insulin dose by 10–20 %. 1, 7
6. Stop basal escalation at 0.5–1.0 U/kg/day and add prandial insulin if targets are not met. 1, 7