Resetting the Correction Factor for Insulin Calculation
The correction factor (insulin sensitivity factor) should be recalculated using the formula 1500/TDD or 1700/TDD based on your current total daily insulin dose, and adjusted if correction doses consistently fail to bring glucose into target range. 1
When to Reset Your Correction Factor
Adjust the correction factor if correction doses do not consistently bring glucose into target range rather than adjusting basal insulin doses. 1 The correction factor addresses acute hyperglycemic excursions and should be modified independently from basal insulin adjustments. 2
Calculation Methods
Standard Formula Approach
- Calculate using 1500/TDD or 1700/TDD where TDD is your total daily insulin dose (basal + all prandial insulin over 24 hours). 1, 3
- The 1500 rule is more commonly used, while the 1700 rule may be appropriate for more insulin-sensitive individuals. 3
- For insulin pump users, the correction factor formula is CorrF = 1960/TDD based on retrospective analysis of optimal glucose control. 3
When to Recalculate
- Recalculate TDD periodically (every few weeks to months) to update correction factors, not daily. 2
- Reassess correction factor parameters every 3-6 months or when significant changes in weight, activity, or overall insulin requirements occur. 4
- For insulin pump users, review and adjust correction factor settings during regular diabetes clinic visits (typically every 3-6 months). 1
Monitoring to Guide Adjustments
Pattern Recognition
- Monitor whether correction doses bring glucose into target range consistently. 1 If they do not, the correction factor needs adjustment regardless of the calculated value.
- Track post-correction glucose levels 2-4 hours after administering correction insulin to assess effectiveness. 1
Avoiding Common Errors
- Do not adjust basal insulin when the problem is inadequate correction dosing. 2 These are separate parameters that should be modified independently.
- Avoid using daily TDD recalculation for correction doses—this introduces unnecessary complexity and variability. 2
- Be aware that correction insulin does not accumulate to steady state and addresses acute hyperglycemic excursions differently than basal insulin. 2
Special Considerations
Clinical Situations Requiring Adjustment
- Duration of diabetes influences correction factor values—longer duration typically requires different sensitivity factors. 1
- Changes in clinical status such as illness, steroid use, or changes in physical activity may temporarily alter insulin sensitivity and require correction factor modification. 5
- Diuresis can temporarily increase insulin sensitivity through volume contraction, meaning correction factors may need adjustment when fluid status normalizes. 4
Integration with Other Parameters
- The correction factor works in conjunction with your carbohydrate-to-insulin ratio (ICR) but should be adjusted separately. 1
- If glucose after meals is consistently out of target, adjust the ICR; if correction doses fail to normalize glucose, adjust the correction factor. 1
- For insulin pump users, approximately 40-60% of TDD should be basal delivery, with the remainder as mealtime and correction boluses. 2
Critical Threshold Awareness
When basal insulin exceeds 0.5 units/kg/day and glucose remains elevated, adding prandial insulin coverage is more appropriate than continuing to escalate correction doses alone. 2, 4 Clinical signals of "overbasalization" include bedtime-to-morning glucose differential ≥50 mg/dL, hypoglycemia, and high glucose variability. 2, 1