What is the recommended approach for managing blood glucose levels in a patient with diabetes using a sliding scale insulin regimen?

Sliding Scale Insulin Should Be Strongly Discouraged in Hospitalized Patients

The sole use of sliding-scale insulin (SSI) in the inpatient hospital setting is strongly discouraged and should be replaced with scheduled basal-bolus insulin regimens for most patients requiring insulin therapy. 1

Why Sliding Scale Insulin Fails

Sliding scale insulin is fundamentally flawed because it treats hyperglycemia reactively after it occurs rather than preventing it, leading to dangerous glucose fluctuations that exacerbate both hyperglycemia and hypoglycemia. 2, 3

• SSI regimens are often used throughout hospital stays without modification, even when control remains poor, demonstrating their inherent ineffectiveness. 2
• In one study, appropriately timed successive glucose measurements documented adequate glucose reduction to target range (90-130 mg/dL) after only 12% of SSI injections, while glucose levels remained elevated after 84% of injections. 4
• Despite persistently elevated blood glucose levels, corresponding adjustments in timing or dose of insulin were made infrequently, with SSI regimens never adjusted in 81% of patients through 5 days of therapy. 4
• The mode of overall glycemic control with SSI was poor, with 51-68% of patients poorly controlled on any given day. 4

The Superior Alternative: Basal-Bolus Insulin

For hospitalized patients with good nutritional intake, a basal-bolus insulin regimen is the preferred treatment. 1

Initial Dosing Strategy

• For insulin-naive patients or those on low-dose insulin at home, start with a total daily dose of 0.3-0.5 units/kg, divided as 50% basal insulin (given once daily) and 50% prandial insulin (divided among three meals). 1, 2
• For patients on high-dose home insulin (≥0.6 units/kg/day), reduce the total daily dose by 20% upon hospitalization to prevent hypoglycemia. 2, 3
• For high-risk patients (elderly >65 years, renal failure, poor oral intake), use lower starting doses of 0.1-0.25 units/kg/day. 1, 2

Titration Protocol

• Adjust basal insulin every 3 days based on fasting glucose patterns, targeting 80-130 mg/dL. 1
• Adjust prandial insulin by 1-2 units every 3 days based on 2-hour postprandial glucose readings, targeting <180 mg/dL. 1
• Point-of-care glucose testing should be performed immediately before meals for patients eating regular meals. 1

Evidence Supporting Basal-Bolus Over SSI

Randomized trials comparing basal-bolus insulin to SSI alone in hospitalized patients with type 2 diabetes demonstrate:

• Better glycemic control: 68% of patients on basal-bolus achieved mean blood glucose <140 mg/dL versus only 38% on SSI alone. 2
• Reduced complications: basal-bolus therapy was associated with reduced postoperative wound infection and acute renal failure. 2
• However, basal-bolus regimens carry a 4-6 times higher risk of hypoglycemia (RR 5.75 for blood glucose ≤70 mg/dL) compared to SSI alone, requiring vigilant monitoring. 3

Limited Acceptable Uses of Sliding Scale Insulin

SSI as monotherapy may be acceptable only in very specific, limited circumstances:

• Patients without pre-existing diabetes who develop mild stress hyperglycemia during hospitalization. 2, 3
• Patients with well-controlled type 2 diabetes (HbA1c <7%) managed by diet alone at home who develop mild hyperglycemia during hospitalization. 3
• Patients who are NPO with no nutritional replacement and only mild hyperglycemia. 3
• Patients who are new to steroids or tapering steroids. 3

Even in these limited scenarios, SSI should be used as a temporary bridge only, with transition to scheduled insulin if hyperglycemia persists. 3

Special Considerations for Poor Oral Intake

For patients with poor oral intake or those receiving nothing by mouth, a basal-plus-correction insulin regimen is the preferred treatment. 1

• Use 0.1-0.25 units/kg/day of basal insulin given once daily. 1, 3
• Add correction doses of rapid-acting insulin before meals or every 6 hours if NPO. 3
• This approach provides continuous background insulin coverage while allowing flexibility for variable nutritional intake. 1

Critical Monitoring and Safety Considerations

• Implement a standardized hospital-wide, nurse-initiated hypoglycemia treatment protocol to immediately address hypoglycemia. 1
• Increase frequency of blood glucose monitoring during any insulin regimen changes. 5
• Self-monitoring of blood glucose plays an essential role in the prevention and management of hypoglycemia. 5
• In patients at higher risk for hypoglycemia and those with reduced symptomatic awareness, increased frequency of blood glucose monitoring is recommended. 5

Common Pitfalls to Avoid

• Never use SSI as monotherapy for patients with established diabetes requiring insulin therapy—this approach leads to dangerous glucose fluctuations and poor outcomes. 1, 2
• Never continue premixed insulin (such as 70/30) in hospitalized patients—randomized trials show unacceptably high rates of iatrogenic hypoglycemia compared to basal-bolus regimens. 2, 3
• Never give rapid-acting insulin at bedtime—this significantly increases the risk of nocturnal hypoglycemia. 1
• Never delay transition from SSI to scheduled insulin when hyperglycemia persists beyond 24-48 hours. 2

Transition Planning

When transitioning from intravenous insulin to subcutaneous insulin:

• A transition protocol to subcutaneous insulin is associated with lower morbidity and costs of care. 1
• Give subcutaneous insulin 1-2 hours before discontinuing intravenous insulin. 1
• Converting to basal insulin at 60-80% of the daily infusion dose has been shown to be effective. 1