Praxis Medical Insights

Est. 2024 • Clinical Guidelines Distilled

Made possible by volunteer editors from the University of Calgary & University of Alberta

Last Updated: 6/18/2025

Insulin Sensitivity Factor Guideline

Introduction to Insulin Sensitivity Factor

  • The insulin sensitivity factor (ISF) in SI units is expressed as mmol/L per unit of insulin, indicating how much blood glucose will decrease with 1 unit of insulin, according to the British Journal of Anaesthesia 1
  • For example, an ISF of 3 mmol/L means that 1 unit of insulin would be expected to decrease blood glucose by 3 mmol/L, as noted by the British Journal of Anaesthesia 1

Calculation of Insulin Sensitivity Factor

  • The ISF is typically calculated based on the total daily insulin dose (TDD) and can be estimated using established formulas, such as the 1800 Rule (for SI units): ISF (mmol/L) = 100/TDD, as reported by Diabetes Care 2
  • Example: For a patient with TDD of 50 units, ISF = 100/50 = 2 mmol/L, illustrating the application of the 1800 Rule 2

Factors Influencing Insulin Sensitivity Factor

  • Physical activity levels influence an individual's insulin sensitivity factor, as noted by the British Journal of Anaesthesia 1
  • Stress levels also impact an individual's insulin sensitivity factor, according to the British Journal of Anaesthesia 1

Implementation of InsF in Insulin Therapy

  • ISF should be programmed into insulin pumps for automated correction calculations, as recommended by the British Journal of Anaesthesia 1
  • For multiple daily injections, ISF guides correction doses based on pre-meal blood glucose, as reported by Diabetes Care 2
  • ISF and insulin-to-carbohydrate ratios are calculated from the total daily dose and reflect the patient's insulin sensitivity, according to the British Journal of Anaesthesia 1

Potential Pitfalls in ISF Implementation

  • Failing to adjust ISF for changes in insulin sensitivity due to exercise, illness, or stress can lead to inadequate glycemic control, as noted by the British Journal of Anaesthesia 1
  • Not recognizing that ISF may need adjustment as total daily insulin requirements change can also impact glycemic control, as reported by the British Journal of Anaesthesia 1 and Diabetes Care 2

REFERENCES

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