What is Insulin Sliding Scale?
Sliding scale insulin (SSI) is a reactive, outdated approach to managing hyperglycemia that administers rapid- or short-acting insulin based on current blood glucose readings, rather than proactively preventing hyperglycemia with scheduled basal insulin—and it should generally not be used as the primary treatment for hospitalized patients with diabetes. 1, 2, 3
Definition and Mechanism
Sliding scale insulin is a regimen where rapid-acting or short-acting insulin is given reactively in response to elevated blood glucose measurements, typically using a predetermined scale (e.g., 2 units for glucose >250 mg/dL, 4 units for glucose >350 mg/dL) 1
This approach treats hyperglycemia after it occurs rather than preventing it, leading to rapid blood glucose fluctuations that exacerbate both hyperglycemia and hypoglycemia 1
SSI has been used for over 80 years without substantial evidence supporting its efficacy as standard care 4
Why Sliding Scale Insulin Is Problematic
Meta-analysis of randomized controlled trials demonstrates that SSI provides no benefits in blood glucose control but is associated with significantly higher mean blood glucose levels and increased incidence of hyperglycemic events compared to other regimens 5
SSI regimens are often continued throughout hospital stays without modification, even when glycemic control remains poor 1
Real-world data shows that SSI achieves good glycemic control in only 2-10% of patients (mean 6%), with the majority (51-68%) remaining poorly controlled 6
Approximately 30% of anticipated insulin administration points have missing documentation or uncertainties regarding execution, timing, or dosing 6
After 621 SSI injections in one study, only 12% successfully reduced elevated glucose to target range (90-130 mg/dL), while 84% remained subtherapeutic 6
Limited Acceptable Uses
The American Diabetes Association identifies only very specific scenarios where SSI alone may be appropriate 1, 2, 3:
Patients without pre-existing diabetes who develop mild stress hyperglycemia during hospitalization 1, 2
Patients with well-controlled type 2 diabetes (HbA1c <7%) managed by diet alone at home who develop only mild hyperglycemia during hospitalization 2, 3
Patients who are NPO with no nutritional replacement and only mild hyperglycemia 1
Patients who are new to steroids or tapering steroids 1
When Sliding Scale Should NEVER Be Used
SSI alone should never be used as the initial approach for patients with type 1 diabetes 1, 3
Patients with type 2 diabetes already on insulin at home require scheduled basal insulin, not reactive correction only 3
SSI monotherapy is inappropriate for any patient with established insulin requirements 3
The Preferred Alternative: Basal-Bolus Approach
The American Diabetes Association recommends a basal-bolus insulin regimen over SSI alone due to superior glycemic control and reduced complications 1
Randomized trials consistently demonstrate better outcomes with basal-bolus approaches: 68% of patients achieved glycemic control (mean glucose <140 mg/dL) with basal-bolus versus only 38% with SSI alone 1
Basal-bolus regimens are associated with reduced postoperative complications, including wound infections and acute renal failure 1
Implementation of basal-bolus insulin via electronic glycemic management systems resulted in 2,434 fewer hypoglycemic events and 40,589 fewer hyperglycemic events compared to SSI, with 21% reduction in hypoglycemia <70 mg/dL and 50% reduction in severe hypoglycemia <50 mg/dL in the ICU 7
Common Pitfalls
Clinicians continue to rely heavily on SSI despite lack of evidence—one hospital reported 95% SSI usage before implementing systematic change 7
The reactive nature of SSI creates a cycle of "chasing" blood glucose rather than preventing excursions 1
SSI regimens in 81% of patients are never adjusted despite persistently elevated glucose levels 6