What sliding‑scale insulin dosing chart should be used for a hospitalized non‑pregnant adult with type 2 diabetes, normal renal function and no severe insulin resistance?

Sliding‑Scale Insulin Chart for Hospitalized Non‑Pregnant Adults with Type 2 Diabetes

Sliding‑scale insulin as monotherapy is explicitly condemned by all major diabetes guidelines and should be immediately discontinued in favor of a scheduled basal‑bolus regimen. 1, 2 Only ≈38% of patients achieve mean glucose <140 mg/dL with sliding‑scale alone versus ≈68% with basal‑bolus therapy, and properly implemented basal‑bolus regimens do not increase hypoglycemia incidence. 1, 3, 2

Why Sliding‑Scale Monotherapy Fails

• 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
• The American Diabetes Association and all major societies explicitly state that sliding‑scale insulin should never be the sole treatment for hospitalized patients requiring insulin. 1, 3, 2
• Randomized trials demonstrate that basal‑bolus therapy reduces postoperative complications including wound infections and acute renal failure compared with sliding‑scale alone. 3

Recommended Basal‑Bolus Regimen Structure

Initial Dosing

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

• Total daily dose: 0.3–0.5 units/kg/day 1, 3, 2
• Split: 50% basal insulin (once daily) + 50% prandial insulin (divided among three meals) 1, 3, 2

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

• Total daily dose: 0.1–0.25 units/kg/day 1, 3, 2
• Same 50:50 split between basal and prandial 1, 2

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

• Reduce total daily dose by 20% upon admission to prevent hypoglycemia 1, 3, 2

Basal Insulin Component

• Use long‑acting analogs (glargine, detemir, or degludec) once daily 1, 2
• Provides continuous background coverage independent of food intake 1, 2

Titration protocol:

• If fasting glucose 140–179 mg/dL: increase by 2 units every 3 days 1, 2
• If fasting glucose ≥180 mg/dL: increase by 4 units every 3 days 1, 2
• Target fasting glucose: 80–130 mg/dL 1, 2

Prandial Insulin Component

• Use rapid‑acting analogs (lispro, aspart, or glulisine) 0–15 minutes before each meal 1, 2
• Initial dose: 4 units before each of three largest meals or 10% of current basal dose 1, 2

Titration protocol:

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

Correction Insulin (Adjunct Only)

Correction doses supplement—never replace—scheduled basal and prandial insulin. 1, 2

Simplified correction scale (add to scheduled prandial dose):

• Pre‑meal glucose >250 mg/dL: add 2 units rapid‑acting insulin 1, 2
• Pre‑meal glucose >350 mg/dL: add 4 units rapid‑acting insulin 1, 2

Individualized correction formula:

• Insulin Sensitivity Factor (ISF) = 1500 ÷ Total Daily Dose 1
• Correction dose = (Current glucose – Target glucose) ÷ ISF 1

Monitoring Requirements

• Patients eating regular meals: check 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 to guide basal insulin adjustments 1, 2
• 2‑hour post‑prandial glucose after each meal to assess prandial adequacy 1, 2

Glycemic Targets

• Overall glucose range: 140–180 mg/dL for non‑critically ill patients 1, 2
• More stringent 110–140 mg/dL may be appropriate if achievable without significant hypoglycemia 2
• Fasting glucose: 80–130 mg/dL 1, 2
• Post‑prandial glucose: <180 mg/dL 1, 2

Hypoglycemia Management

• Treat any glucose <70 mg/dL immediately with 15 g fast‑acting carbohydrate, recheck in 15 minutes, repeat if needed 1, 2
• If unexplained hypoglycemia occurs, reduce the implicated insulin dose by 10–20% immediately 1, 2
• Document every hypoglycemic episode for quality tracking 2

Special Situations

Patients with Poor Oral Intake or NPO

• Use basal‑plus‑correction regimen: basal insulin at reduced dose (0.1–0.25 units/kg/day) plus correction doses only 1, 2
• Never withhold basal insulin in type 1 diabetes or insulin‑dependent type 2 diabetes, even when NPO, to prevent diabetic ketoacidosis 1, 2
• Check glucose every 4–6 hours 2

Peri‑operative Management

• Morning of surgery: give 50% of usual NPH dose or 75–80% of usual long‑acting analog dose 2
• While NPO peri‑operatively: monitor glucose every 2–4 hours and supplement with short‑ or rapid‑acting insulin as needed 2
• Target peri‑operative glucose: 80–180 mg/dL 2

Transition from IV Insulin

• Give subcutaneous basal insulin 2–4 hours before stopping IV infusion to prevent rebound hyperglycemia 2
• Convert to basal insulin at 60–80% of total daily IV dose, split 50% basal and 50% prandial 2

Critical Pitfalls to Avoid

• Never use sliding‑scale insulin as monotherapy in any hospitalized patient—it is condemned by all major diabetes guidelines 1, 3, 2
• Never give rapid‑acting insulin at bedtime as a sole correction dose—this markedly raises nocturnal hypoglycemia risk 1, 2
• Do not delay adding prandial insulin when basal insulin alone fails to meet targets or when basal dose reaches 0.5–1.0 units/kg/day 1, 2
• Do not continue basal escalation beyond 0.5–1.0 units/kg/day without addressing post‑prandial hyperglycemia—this causes "over‑basalization" with increased hypoglycemia risk 1, 2
• Do not rely solely on correction doses without adjusting scheduled basal and prandial insulin 1, 2

Expected Clinical Outcomes

• With properly implemented basal‑bolus therapy, ≈68% of patients achieve mean glucose <140 mg/dL versus ≈38% with sliding‑scale alone 1, 3, 2
• Basal‑bolus therapy does not increase hypoglycemia incidence when titrated appropriately 1, 2
• Randomized trials show reduced hospital complications including wound infections and acute renal failure with basal‑bolus versus sliding‑scale 3

Adjunctive Therapy

• Continue metformin at maximum tolerated dose (up to 2,000–2,550 mg daily) unless contraindicated by acute illness, renal impairment, or contrast use—this reduces total insulin requirements by 20–30% 1, 3
• Discontinue sulfonylureas when initiating basal‑bolus insulin to avoid additive hypoglycemia risk 1