What is the insulin sliding scale for a patient with Diabetes Mellitus (DM) who is Nil Per Os (NPO)?

Insulin Management for NPO Diabetic Patients

For NPO diabetic patients, avoid sliding scale insulin alone and instead use a basal-plus approach with 0.1-0.25 units/kg/day of basal insulin supplemented with correction doses of rapid-acting insulin for hyperglycemia. 1

Why Sliding Scale Alone is Inadequate

• Sliding scale insulin (SSI) alone is a reactive approach that treats hyperglycemia after it occurs, leading to clinically significant hyperglycemia with only 38% of patients achieving mean blood glucose <140 mg/dL compared to 68% with basal-bolus regimens 2
• SSI monotherapy is associated with increased hospital complications including postoperative wound infections and acute renal failure 2
• The American Diabetes Association explicitly recommends against using SSI alone as the initial approach for hospitalized diabetic patients 1

Recommended Approach for NPO Patients

Basal-Plus Regimen:

• Administer basal insulin at 0.1-0.25 units/kg/day (lower end of dosing range for NPO status) 1
• Add correction doses of rapid-acting insulin for pre-meal or scheduled hyperglycemia 1
• This approach is specifically recommended by Diabetes Canada for patients with poor oral intake or NPO status 1

Dosing Adjustments:

• Use lower doses (toward 0.1 units/kg/day) for patients at higher risk of hypoglycemia, including older adults or those with renal failure 1
• For patients already on higher home insulin doses (≥0.6 units/kg/day), reduce the total daily dose by 20% during hospitalization 1, 2

Correction Dose Algorithm

Simplified Correction Scale:

• Give 2 units of short- or rapid-acting insulin for pre-meal glucose >250 mg/dL 1
• Give 4 units of short- or rapid-acting insulin for pre-meal glucose >350 mg/dL 1
• If correction doses are frequently required, increase the scheduled basal insulin dose accordingly 1

When SSI Might Be Acceptable

The American Diabetes Association suggests SSI might be acceptable only in these limited scenarios: 1

• Patients with mild stress hyperglycemia without pre-existing diabetes
• Patients with well-controlled diabetes (HbA1c <7%) on minimal home therapy who have mild hyperglycemia during hospitalization
• Patients who are NPO with no nutritional replacement and only mild hyperglycemia
• Patients who are new to steroids or tapering steroids

Critical Safety Considerations

• The basal-plus approach carries a 4-6 times higher hypoglycemia risk than SSI alone, with a risk ratio of 5.75 (95% CI 2.79-11.83) for blood glucose ≤70 mg/dL 2
• Implement hospital-wide hypoglycemia protocols for glucose <70 mg/dL 2
• Review the treatment regimen after any glucose <70 mg/dL 2
• Monitor blood glucose every 4-6 hours while NPO 1

Transitioning from IV Insulin

• Administer subcutaneous basal insulin 2-4 hours before stopping IV infusion 2
• Convert at 60-80% of daily IV infusion dose 2
• Calculate the daily dose based on the average insulin infused during the previous 12 hours 1

Common Pitfalls to Avoid

• Do not use premixed insulin (70/30) in hospitals due to unacceptably high hypoglycemia rates 1
• Do not continue SSI throughout hospital stays without modification when control remains poor 1
• Do not use SSI alone for patients with type 1 diabetes under any circumstances 1
• Avoid abrupt discontinuation of basal insulin when patients become NPO, as this leads to rebound hyperglycemia 1