Insulin sensitivity factor is best thought of as the drop in glucose level (in mg/dL) that your child can expect from 1 unit of insulin, and is used together with the blood glucose target to determine how much extra insulin to take at mealtime to bring high glucose readings back down to target.
Example:Imaginary settings for a child:
ICR: 1:10 (1 unit of rapid acting insulin for 10g CHO)
Target glucose: 150 mg/dL
Insulin sensitivity factor: 50 mg/dL
Current readings and meal plan:
Glucose 175 mg/dL
CHO to be consumed: 70g
In the above scenario, the Smart Insulin Pen dosing assistant would advise 7.5 units of insulin.
Calculation: 70g/10 = 7 units for CHO
(175-150)/50 = 0.5 units for correction
Total = 7.5 units