What is the typical sliding scale insulin (SSI) regimen used in hospitals?

Sliding Scale Insulin in Hospitals: Current Practice and Evidence

Direct Answer

Sliding scale insulin (SSI) alone should not be used in hospitals, as it is strongly discouraged by all major guidelines and has been shown to be ineffective for glycemic control. 1 Most hospitals that still use SSI typically employ regular insulin dosed according to pre-meal glucose ranges (e.g., 2-4 units for glucose 200-250 mg/dL, 4-6 units for 250-300 mg/dL, etc.), but this reactive approach leads to poor outcomes and should be replaced with basal-bolus regimens. 1, 2

Why SSI Alone Fails

The traditional sliding scale approach has fundamental flaws that make it unsuitable for hospital use:

• SSI treats hyperglycemia reactively after it occurs rather than preventing it, leading to rapid glucose fluctuations that worsen both hyperglycemia and hypoglycemia 1, 3
• SSI regimens prescribed on admission typically remain unchanged throughout hospitalization despite poor control, with no mechanism for dose adjustment 1
• Meta-analysis of 1,322 patients showed SSI resulted in significantly higher mean blood glucose levels (27.33 mg/dL higher) and increased hyperglycemic events compared to other regimens 2
• Only 38% of patients on SSI alone achieved target glucose control (<140 mg/dL) versus 68% with basal-bolus insulin 1, 3

What Hospitals Should Use Instead

For Non-Critically Ill Patients with Good Oral Intake

Basal-bolus-plus-correction regimen is the preferred approach:

• Start with total daily insulin dose of 0.3-0.5 units/kg for insulin-naive patients 4, 3
• Divide dose: 50% as basal insulin (once daily) and 50% as rapid-acting prandial insulin (split before meals) 3
• Add correction doses of rapid-acting insulin for pre-meal hyperglycemia using a modified scale 5, 4
• This approach reduced postoperative complications including wound infections and acute renal failure compared to SSI 3

For Non-Critically Ill Patients with Poor Oral Intake or NPO

Basal-plus-correction regimen is preferred:

• Use lower total daily insulin dose of 0.1-0.25 units/kg per day as basal insulin 5, 4
• Add correction doses of rapid-acting insulin only when needed 1, 5
• This approach is safer for patients at higher risk of hypoglycemia (elderly, renal failure, poor intake) 4, 3

For Critically Ill Patients

Continuous intravenous insulin infusion is the most effective method:

• Target blood glucose range of 140-180 mg/dL 4, 3
• Regular crystalline insulin is used (no advantage to rapid-acting analogs IV) 1

Modified Correction Scales (When Used Appropriately)

When correction insulin is used as part of a comprehensive regimen (not as monotherapy):

Standard Correction Scale

• For pre-meal glucose >250 mg/dL: give 2 units of rapid-acting insulin 3
• For pre-meal glucose >350 mg/dL: give 4 units of rapid-acting insulin 3

Lower-Dose Scale for High-Risk Patients

• For patients >65 years, renal failure, or poor oral intake: start with 1-2 units for lower glucose elevations 4
• Patients with renal impairment have 4-6 times higher risk of hypoglycemia and require modified scales 5

Critical Implementation Points

Dose adjustments for special populations:

• For patients on high home insulin doses (≥0.6 units/kg/day), reduce total daily dose by 20% during hospitalization to prevent hypoglycemia 4, 3
• For patients with renal impairment (eGFR <30), use lower doses and more conservative correction scales 5

When transitioning from IV to subcutaneous insulin:

• Give subcutaneous basal insulin 2-4 hours before discontinuing IV insulin 1
• Calculate dose as 60-80% of the average 24-hour IV insulin infusion rate 1

Common Pitfalls to Avoid

• Never use SSI alone for patients with type 1 diabetes—this is dangerous and can lead to diabetic ketoacidosis 4, 3
• Avoid premixed insulin (70/30 NPH/regular) in hospitals due to unacceptably high hypoglycemia rates 1, 4
• Do not continue the same SSI regimen throughout hospitalization without modification despite persistent hyperglycemia 1
• Basal-bolus regimens carry 12-30% risk of mild hypoglycemia in controlled settings, requiring vigilant monitoring 4, 3

Evidence Quality

The recommendation against SSI alone is supported by:

• Multiple high-quality guidelines from the American Diabetes Association (2019), American College of Physicians (2011), and VA/DoD (2017) 1
• Cochrane systematic review of 8 RCTs with 1,048 participants showing SSI resulted in worse glycemic control 6
• Meta-analysis demonstrating 27.33 mg/dL higher mean glucose with SSI versus other regimens 2