When increasing insulin by 20% to correct hyperglycemia in an inpatient, should the increase be based on total daily insulin or only basal and scheduled bolus insulin doses?

Insulin Dose Adjustment for Inpatient Hyperglycemia Correction

When increasing insulin by 20% to correct hyperglycemia in hospitalized patients, the adjustment should be based on the scheduled insulin doses only (basal and scheduled bolus insulin), not including the sliding scale or correction insulin doses.

Rationale for Adjusting Only Scheduled Insulin

The 20% insulin dose adjustment recommendation comes from evidence-based guidelines for managing inpatient hyperglycemia. According to The Lancet Diabetes and Endocrinology (2021), when adjusting insulin doses to correct hyperglycemia, the focus should be on modifying the scheduled components of the insulin regimen 1:

• Basal insulin: Long-acting insulin given once or twice daily
• Scheduled bolus insulin: Rapid-acting insulin given before meals

The sliding scale or correction insulin is designed to address acute, temporary blood glucose elevations and should not be included when calculating the 20% increase. Including correction doses in this calculation could lead to:

1. Overestimation of insulin requirements
2. Increased risk of hypoglycemia
3. Inappropriate dose escalation

Implementation of Insulin Adjustment

Step 1: Calculate Current Scheduled Insulin

• Add together the total daily dose of basal insulin and scheduled mealtime bolus insulin
• Do NOT include any sliding scale or correction doses given

Step 2: Apply the 20% Increase

• Multiply the total scheduled insulin by 1.2
• Example: If a patient receives 30 units of basal insulin and 15 units of scheduled mealtime insulin (total 45 units), the 20% increase would be to 54 units

Step 3: Distribute the Increased Dose

• Maintain the same proportion of basal to bolus insulin
• Example: If the original regimen was 2/3 basal (30 units) and 1/3 bolus (15 units), the new doses would be 36 units basal and 18 units bolus

Special Considerations

Risk of Hypoglycemia

The basal-bolus approach, while effective for glycemic control, carries a 12-30% risk of mild hypoglycemia in controlled settings 1. When increasing insulin doses:

• Monitor blood glucose more frequently after adjustment
• Consider lower increases (10-15%) in high-risk patients:
  • Elderly patients (>65 years)
  • Patients with renal insufficiency
  • Those with poor oral intake

Sliding Scale Limitations

Sliding scale insulin alone is not recommended as monotherapy for inpatient hyperglycemia management 1. However, it serves an important role as a supplement to scheduled insulin therapy:

• It helps identify patterns requiring adjustment to scheduled insulin
• It provides coverage for unexpected hyperglycemia
• When correction doses are frequently required, this indicates the need to increase scheduled insulin doses 1

Recent Evidence on Insulin Adjustments

Recent research suggests that more aggressive insulin adjustments may be beneficial in some cases. A 2025 retrospective study found that increases of 44-100% in total daily insulin dose were more effective at achieving glycemic targets than the typical 10-22% increases in hospitalized patients with hyperglycemia 2. However, until this is validated in prospective studies, the standard 20% adjustment of scheduled insulin remains the recommended approach based on established guidelines.

Common Pitfalls to Avoid

1. Including correction insulin in calculations: This can lead to inappropriate dose escalation
2. Failing to adjust both basal and bolus components: Both components should be increased proportionally
3. Using premixed insulin: This has been associated with high rates of hypoglycemia and is not recommended for inpatient use 1
4. Relying solely on sliding scale: This reactive approach leads to glucose fluctuations and poor control 1

By focusing the 20% increase on scheduled insulin components only, you can more safely and effectively correct inpatient hyperglycemia while minimizing the risk of hypoglycemic events.