What sliding‑scale insulin regimen should be used for patients who are NPO (nothing by mouth) and not taking oral intake?

Insulin Management for NPO Patients

For hospitalized patients who are NPO (nothing by mouth) or have poor oral intake, a basal insulin regimen with correction doses—not sliding-scale insulin alone—is the evidence-based standard of care. 1

Recommended Insulin Regimen

Basal-Plus-Correction Approach

The preferred treatment for noncritically ill hospitalized patients who are NPO is basal insulin or a basal-plus-correction insulin regimen. 1 This approach provides:

• Basal insulin (glargine, detemir, or degludec) administered once daily to suppress hepatic glucose production and prevent fasting hyperglycemia 1
• Correction insulin (rapid-acting analogs: lispro, aspart, or glulisine) given only when point-of-care glucose exceeds predefined thresholds 1, 2

Why Sliding-Scale Insulin Alone Is Inadequate

Sole use of sliding-scale insulin in the inpatient hospital setting is strongly discouraged. 1 The evidence is unequivocal:

• Only 38% of patients on sliding-scale monotherapy achieve mean glucose <140 mg/dL, versus 68% with scheduled basal-bolus regimens 2, 3
• Sliding-scale insulin treats hyperglycemia reactively after it occurs rather than preventing it, leading to dangerous glucose fluctuations 2, 3
• Randomized controlled trials demonstrate that basal-bolus treatment improves glycemic control and reduces hospital complications compared with sliding-scale insulin 1

Practical Implementation

Initial Dosing for NPO Patients

For insulin-naïve or low-dose insulin patients:

• Start with 0.3–0.5 units/kg/day as total daily dose, giving 50% as basal insulin 2
• For a 70 kg patient, this translates to approximately 10–18 units of basal insulin once daily 2

For high-risk populations (elderly >65 years, renal impairment, poor oral intake):

• Use lower starting doses of 0.1–0.25 units/kg/day to prevent hypoglycemia 2

For patients on high-dose home insulin (≥0.6 units/kg/day):

• Reduce the total daily dose by 20% upon admission to prevent hypoglycemia 2

Correction Insulin Protocol

Use a simplified correction scale as an adjunct to basal insulin:

• Administer 2 units of rapid-acting insulin when glucose >250 mg/dL (13.9 mmol/L) 2
• Administer 4 units of rapid-acting insulin when glucose >350 mg/dL (19.4 mmol/L) 2

Alternatively, calculate individualized correction doses:

• Insulin sensitivity factor (ISF) = 1500 ÷ total daily dose (for regular insulin) or 1700 ÷ total daily dose (for rapid-acting analogs) 2
• Correction dose = (Current glucose − Target glucose) ÷ ISF 2

Monitoring Requirements

For NPO patients:

• Check point-of-care glucose every 4–6 hours 1, 2
• Target glucose range: 140–180 mg/dL for most noncritically ill hospitalized patients 1, 2
• More stringent targets of 110–140 mg/dL may be appropriate for selected patients if achievable without significant hypoglycemia 1

Titration Strategy

Basal Insulin Adjustment

Titrate basal insulin based on fasting glucose patterns:

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

If hypoglycemia occurs (glucose <70 mg/dL):

• Reduce the implicated insulin dose by 10–20% immediately 1, 2
• Identify and address the precipitating cause 2

Special Considerations

Perioperative Management

For patients undergoing surgery:

• Administer 50% of the usual NPH dose or 75–80% of long-acting analog dose the morning of surgery 1
• Alternatively, reduce basal insulin by approximately 25% the evening before surgery to lower hypoglycemia risk while maintaining target glucose 2
• Monitor glucose every 2–4 hours while NPO and dose with short- or rapid-acting insulin as needed 1
• Target perioperative glucose range: 80–180 mg/dL 1, 2

Transitioning from IV to Subcutaneous Insulin

When discontinuing intravenous insulin:

• Give the first subcutaneous basal insulin dose 2–4 hours before stopping the IV infusion to avoid rebound hyperglycemia 2
• Calculate total subcutaneous dose as half of the IV insulin infused over 24 hours 2
• Give 50% as basal insulin once in the evening, and divide the remaining 50% by 3 for rapid-acting analog before each meal (if eating) 2

Patients on Enteral or Parenteral Nutrition

For continuous enteral/parenteral feeding:

• A reasonable starting point is 5 units of NPH/detemir every 12 hours or 10 units of insulin glargine every 24 hours 2
• Human regular insulin may be added directly to parenteral nutrition solution if >20 units of correctional insulin have been required 1

Critical Pitfalls to Avoid

Never use sliding-scale insulin as monotherapy in hospitalized patients requiring insulin therapy—this approach is condemned by all major diabetes guidelines and leads to poor outcomes 1, 2, 4, 3

Never completely withhold basal insulin in NPO patients, as it suppresses hepatic glucose production independent of food intake and prevents hyperglycemia and ketosis 2

Never administer rapid-acting insulin at bedtime as a sole correction dose, as this markedly raises nocturnal hypoglycemia risk 2

Do not delay transition to scheduled insulin when glucose values are consistently >250 mg/dL—this prolongs exposure to severe hyperglycemia and increases complication risk 2

Hypoglycemia Management

Establish a hypoglycemia protocol:

• Treat any glucose <70 mg/dL immediately with 15 grams of fast-acting carbohydrate 2
• For NPO patients unable to take oral carbohydrates, treat with intravenous dextrose (D10W at 40 mL/h or D5W at higher infusion rate) 2
• Document every hypoglycemic episode in the medical record for quality tracking 2
• Promptly review and adjust the insulin regimen whenever documented glucose <70 mg/dL occurs 2

Recognize that 78% of patients using basal insulin experience hypoglycemia peaking between midnight and 6:00 AM, yet 75% have no basal insulin dose adjustment before the next administration 1