#822 The Math Behind Setting Insulin Sensitivity Factor

Setup Math

Setting up insulin sensitivity factors involves understanding the math behind it, particularly the 1800 rule. Scott Benner and Jenny Smith explain that you divide your total daily insulin dose into 1800 to determine a starting point for your sensitivity factor. For example, dividing 30 units into 1800 results in a sensitivity factor of 60, which may need adjustment based on individual needs and time of day 1. Jenny emphasizes the importance of revisiting these calculations regularly, as factors like undigested food or dehydration can influence effectiveness 1.

Many people start by just saying it's the 1800 rule, right. So you're essentially going to take again what is your total daily dose, and you're going to divide that into 1800 to get a starting point for your correction or your sensitivity factor.

--- Jenny Smith

Scott and Jenny also highlight the significance of understanding these calculations through their pro tip series, which began in 2019 2.

   

Algorithm Impact

Algorithm-based pumps and loop systems significantly influence insulin sensitivity settings. Jenny Smith notes that personal activity levels and metabolic needs can necessitate adjustments to standard rules like the 1800 rule, sometimes requiring a more conservative approach with a 2000 rule 3. Scott Benner shares an example involving his daughter, Arden, whose insulin sensitivity needed adjustments based on her activity levels at college 3.

Life is ever changing. It is. You will continue to grow. You will continue to get older. We don't, unfortunately, get younger. Your insulin needs will shift and change.

--- Jenny Smith

Scott also discusses the challenges of using algorithmic systems like Control IQ and Omnipod 5, which have proprietary settings that can complicate understanding insulin sensitivity adjustments 4.