What is the best type of insulin to use for a sliding scale regimen in a patient with hyperglycemia?

Best Insulin for Sliding Scale Regimens

Rapid-acting insulin analogs (insulin lispro or insulin aspart) are the best choice for sliding scale regimens when correction insulin is needed, but sliding scale insulin alone should NOT be used as the primary treatment approach for hospitalized patients with diabetes. 1

Critical Limitation of Sliding Scale Monotherapy

• Sliding scale insulin (SSI) as the sole treatment is explicitly condemned by all major diabetes guidelines because it treats hyperglycemia reactively after it occurs rather than preventing it, leading to dangerous glucose fluctuations and poor glycemic control 1, 2
• SSI alone achieved glycemic control (mean blood glucose <140 mg/dL) in only 38% of patients versus 68% with basal-bolus therapy 1
• Research demonstrates that SSI regimens are "widely variable, often ineffectual, and prone to deficiencies in monitoring, documentation, and prescribing soundness" 3

When Sliding Scale May Be Acceptable

SSI as monotherapy is appropriate only in very limited circumstances 1, 2:

• Patients without pre-existing diabetes who develop mild stress hyperglycemia during hospitalization 1, 2
• Patients with well-controlled type 2 diabetes (HbA1c <7%) on diet alone or minimal home therapy who have mild hyperglycemia during hospitalization 1, 2
• Patients who are NPO with no nutritional replacement and only mild hyperglycemia 1
• Patients who are new to steroids or tapering steroids 1

Recommended Insulin Type for Correction Doses

When correction insulin is needed as part of a scheduled regimen, rapid-acting insulin analogs are superior to regular human insulin 1:

• Insulin lispro or insulin aspart are the preferred rapid-acting analogs 4, 5
• These analogs have a faster onset (0.25-0.5 hours), peak action at 1-3 hours, and shorter duration (3-5 hours) compared to regular human insulin 6, 4
• Rapid-acting analogs provide better postprandial glycemic control and 12% reduction in hypoglycemia frequency compared to regular human insulin 6, 4
• They can be administered immediately before meals (0-15 minutes) rather than 30 minutes before, providing greater convenience 6, 4, 5

Proper Insulin Regimen Structure

All hospitalized patients requiring insulin should be on a scheduled regimen with basal, prandial, and correction components—not correction insulin alone 1, 6:

Basal-Plus Approach (Preferred for Most Hospitalized Patients)

• Basal insulin dose: 0.1-0.25 units/kg/day given once daily 1, 2
• Correction doses of rapid-acting insulin (lispro or aspart) given before meals or every 6 hours if NPO 2
• This approach is superior to SSI alone for most hospitalized patients requiring insulin 2

Simplified Sliding Scale Dosing (When Used as Correction Only)

• Give 2 units of rapid-acting insulin for premeal glucose >250 mg/dL 1, 6
• Give 4 units of rapid-acting insulin for premeal glucose >350 mg/dL 1, 6
• These correction doses should be in addition to scheduled basal and prandial insulin, not as monotherapy 6

Basal-Bolus Regimen (For Patients with Good Oral Intake)

• Total daily dose: 0.3-0.5 units/kg/day, divided 50% basal and 50% prandial 1, 6
• Use rapid-acting insulin analogs (lispro or aspart) for prandial coverage 1, 6
• Add correction doses using the same rapid-acting analog for hyperglycemia 1, 6

Comparison: Regular vs. Rapid-Acting Insulin for Sliding Scale

No significant difference in glycemic control was found between regular and lispro insulin sliding scales when used as monotherapy, but both were inadequate to achieve recommended glycemic targets 7:

• Average blood glucose: regular insulin 157.78 mg/dL vs. lispro 152.04 mg/dL (P>.05) 7
• Both insulin sliding scales used as the only inpatient treatment are inadequate to achieve current recommended glycemic targets 7
• This reinforces that the type of insulin matters less than the regimen structure—scheduled basal-bolus therapy is essential 1

Critical Pitfalls to Avoid

• Never use sliding scale insulin as monotherapy except in the very limited circumstances described above 1, 2
• Never give rapid-acting insulin at bedtime for correction, as this significantly increases nocturnal hypoglycemia risk 6
• Never continue SSI regimens without modification when control remains poor—this occurs in 81% of patients but leads to persistent hyperglycemia 3
• Reduce total daily insulin by 20% during hospitalization for patients on high-dose insulin at home (≥0.6 units/kg/day) to prevent hypoglycemia 1, 2

Safety Considerations

• Basal-bolus regimens provide better glycemic control but carry 4-6 times higher risk of hypoglycemia compared to SSI alone (RR 5.75 for blood glucose ≤70 mg/dL) 2
• Use lower doses (0.1-0.25 units/kg/day) for high-risk patients: elderly (>65 years), renal failure, or poor oral intake 1, 6
• Target glucose range: 140-180 mg/dL for most hospitalized patients 1