Should I increase my Insulin Sensitivity Factor (ISF) on my insulin pump?

Insulin Sensitivity Factor (ISF) Adjustment for Insulin Pump Users

Yes, you should increase your Insulin Sensitivity Factor (ISF) if your current setting of 1:10 required 13 units to correct your blood glucose. This indicates your current ISF setting is underestimating your insulin sensitivity.

Understanding ISF and Correction Dosing

ISF represents how much one unit of insulin will lower your blood glucose. When your actual correction needs (13 units) exceed what your programmed ISF calculates (10 units), this suggests your current ISF setting is too low.

Key Considerations for ISF Adjustment:

1. Current Evidence: According to the American Diabetes Association's Standards of Care 1, correction insulin dosing should be adjusted when:

   • Correction doses don't consistently bring glucose into target range
   • ISF settings don't accurately reflect your body's response to insulin

2. Signs Your ISF Needs Adjustment:

   • Needing more insulin than calculated for corrections
   • Consistent post-correction hyperglycemia
   • Glucose not returning to target range after corrections

How to Adjust Your ISF

1. Calculate New ISF Value:

   • Current ISF = 1:10 (1 unit lowers glucose by 10 mg/dL)
   • Actual response = 1:7.7 (calculated as: 100÷13 = ~7.7)
   • Recommended adjustment: Increase ISF to approximately 1:8

2. Implementation Process:

   • Make incremental changes (start with 1:8 or 1:9)
   • Monitor correction responses for 3-5 days
   • Further adjust if needed based on response patterns

3. Monitor for Overbasalization:

   • The 2023 ADA guidelines 1 warn about overbasalization when basal insulin exceeds 0.5 units/kg/day
   • Watch for high bedtime-morning glucose differentials
   • Monitor for hypoglycemia after corrections

Special Considerations

• Timing: Make ISF adjustments during periods of normal activity (not during illness, unusual stress, or significant exercise changes)
• Meal Timing: Ensure corrections aren't being affected by food absorption
• Infusion Set Issues: Rule out infusion set failures as noted in AID system limitations 1
• Time of Day: Consider whether your insulin sensitivity varies throughout the day (may need different ISF settings for different times)

When to Consult Healthcare Provider

• If multiple adjustments don't resolve the issue
• If you experience unexplained hypoglycemia after adjustment
• If you notice significant variability in correction responses
• If total daily insulin dose changes significantly

Remember that ISF is a dynamic setting that may need periodic reassessment as your insulin sensitivity can change over time due to weight changes, activity levels, stress, and other factors.