At what blood glucose levels do we initiate a sliding scale insulin regimen and insulin infusion in hospitalized patients with hyperglycemia?

Blood Glucose Thresholds for Insulin Initiation in Hospitalized Patients

For hospitalized patients, initiate insulin therapy when blood glucose persistently exceeds 180 mg/dL on two separate measurements, and transition to continuous intravenous insulin infusion for critically ill patients requiring intensive glycemic management to maintain glucose between 140-180 mg/dL. 1

Sliding Scale Insulin Initiation

When to Start Sliding Scale Insulin

• Blood glucose threshold: >180 mg/dL (10.0 mmol/L) on two occasions 1
• However, sliding scale insulin (SSI) alone is strongly discouraged as the sole method of glycemic control in hospitalized patients 1
• SSI should only be used as a correction component alongside basal insulin, not as monotherapy 1

Preferred Approach Over SSI Alone

• Basal-bolus regimen is preferred for noncritically ill patients with good nutritional intake, consisting of scheduled basal insulin plus prandial and correction doses 1
• Basal-plus correction insulin is recommended for patients with poor oral intake or those NPO (nothing by mouth) 1
• For patients with mild hyperglycemia (blood glucose <200 mg/dL), a basal-plus approach with corrective doses may be more appropriate than full basal-bolus to reduce hypoglycemia risk 1

Insulin Infusion Initiation

Critical Care Setting

• Start continuous IV insulin infusion at blood glucose ≥180 mg/dL (10.0 mmol/L) in critically ill patients 1
• Target glucose range: 140-180 mg/dL (7.8-10.0 mmol/L) for the majority of critically ill patients 1
• More stringent targets of 110-140 mg/dL may be considered for select patients (e.g., post-cardiac surgery) if achievable without significant hypoglycemia 1
• Avoid targets <110 mg/dL due to 10-15 fold increased hypoglycemia risk and potential increased mortality demonstrated in the NICE-SUGAR trial 1

Noncritically Ill Patients

• Initiate insulin therapy at blood glucose ≥180 mg/dL persistently 1
• Target range: 140-180 mg/dL for most noncritically ill patients, with premeal glucose <140 mg/dL and random glucose <180 mg/dL 1
• Expert consensus supports a broader target of 100-180 mg/dL for noncritically ill patients with new hyperglycemia or known diabetes 1
• Subcutaneous scheduled insulin regimens are preferred over IV infusion outside the ICU 1

Key Clinical Considerations

Hyperglycemia Definition

• Hyperglycemia is defined as blood glucose >140 mg/dL (7.8 mmol/L) in hospitalized patients 1
• Persistent levels above this threshold should prompt dietary modifications or medication adjustments 1

Hypoglycemia Prevention

• Reassess insulin regimen when blood glucose falls below 100 mg/dL as this predicts hypoglycemia within 24 hours 1
• Modify regimen when blood glucose <70 mg/dL unless easily explained by missed meals 1
• Never administer insulin when blood glucose is already <70 mg/dL 2
• The basal-bolus approach carries 4-6 times higher hypoglycemia risk than SSI alone, necessitating careful monitoring 1

Common Pitfalls to Avoid

• Do not use SSI as monotherapy - it is ineffective and excludes the critical basal insulin component 1, 3
• Do not target glucose <110 mg/dL in critically ill patients due to excessive hypoglycemia risk without mortality benefit 1
• Do not continue home insulin doses unchanged - reduce total daily dose by 20% in patients on ≥0.6 U/kg/day at home to prevent hypoglycemia 1, 2
• Do not delay insulin adjustment - 65% of patients with hyper- or hypoglycemia have no insulin order changes made, representing a major quality gap 4

Insulin Dosing Strategy

• For insulin-naive patients or those on low doses: start with 0.3-0.5 U/kg total daily dose, with half as basal and half divided before meals 1
• Lower doses (0.1-0.25 U/kg) are appropriate for patients at high hypoglycemia risk (elderly >65 years, renal failure, poor oral intake) 1
• Use validated protocols with predefined adjustment algorithms rather than ad hoc ordering 1