What is the recommended insulin regimen for a patient with diabetes who requires a sliding scale of insulin?

Sliding Scale Insulin Should Not Be Used as Monotherapy

Sliding scale insulin (SSI) alone is ineffective and should be replaced with scheduled basal-bolus insulin therapy for hospitalized patients with established insulin requirements. 1, 2, 3

Why Sliding Scale Insulin Fails

Sliding scale insulin is fundamentally flawed because it treats hyperglycemia reactively after it has already occurred, rather than preventing it 1, 2. This reactive approach leads to:

• Rapid blood glucose fluctuations that exacerbate both hyperglycemia and hypoglycemia 1
• Clinically significant hyperglycemia with only 38% of patients achieving mean blood glucose <140 mg/dL, compared to 68% with basal-bolus therapy 1, 2
• Increased hospital complications including postoperative wound infections and acute renal failure 2, 3
• SSI regimens prescribed on admission typically continue unchanged throughout hospitalization even when control remains poor 1

The Recommended Alternative: Basal-Bolus Insulin

For Hospitalized Patients with Good Oral Intake

Start with a total daily dose of 0.3-0.5 units/kg/day, divided as 50% basal insulin (once daily) and 50% prandial insulin (divided before meals). 2, 3

• For patients already on high home insulin doses (≥0.6 units/kg/day), reduce the total daily dose by 20% during hospitalization to prevent hypoglycemia 2, 4
• For high-risk patients (elderly >65 years, renal failure, poor oral intake), use lower doses of 0.1-0.25 units/kg/day 2, 4

For Patients with Poor or No Oral Intake

Use a basal-plus approach: 0.1-0.25 units/kg/day of basal insulin plus correction doses of rapid-acting insulin for hyperglycemia. 2

Titration Protocol

• Increase basal insulin by 2 units every 3 days if fasting glucose is 140-179 mg/dL 2, 4
• Increase basal insulin by 4 units every 3 days if fasting glucose is ≥180 mg/dL 2, 4
• Target fasting glucose: 80-130 mg/dL 2, 4
• Adjust prandial insulin by 1-2 units every 3 days based on 2-hour postprandial glucose, targeting <180 mg/dL 2, 4

When Sliding Scale Insulin Might Be Acceptable

SSI may be appropriate only in very limited circumstances 2:

• 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

Even in these situations, SSI should only be used as a supplement to scheduled insulin, never as monotherapy. 1, 2

Critical Safety Considerations

The basal-bolus approach carries higher hypoglycemia risk than SSI alone (risk ratio 5.75,95% CI 2.79-11.83 for blood glucose ≤70 mg/dL) 3. To mitigate this:

• Implement hospital-wide hypoglycemia protocols for glucose <70 mg/dL 3
• Review the treatment regimen after any glucose <70 mg/dL 3
• Use basal-plus rather than full basal-bolus for fasting patients or those undergoing procedures 3

Common Pitfalls to Avoid

• Never continue SSI as monotherapy throughout hospitalization – this is explicitly condemned by all major diabetes guidelines 1, 2, 3, 5
• Never give rapid-acting insulin at bedtime – this significantly increases nocturnal hypoglycemia risk 2, 4
• Never use premixed insulin in hospitals – randomized trials show unacceptably high hypoglycemia rates compared to basal-bolus regimens 2, 4
• Never abruptly discontinue oral medications when starting insulin – continue metformin unless contraindicated 6, 7