If you measure blood glucose units in mg/dL you can get help with the calculation by pressing the buttons “Help with the 1800-rule” and “Help with the 500-rule”.
The rules can be summarised as follows;
- The 1800 rule is used to calculate your insulin sensitivity factor, that is, how many mg/dl 1 unit of insulin lowers the blood glucose level. Insulin sensitivity factor, equals 1800 divided by the total daily dose.
- The 500 rule is a calculation where 500 is divided by your total daily dose to give you the number of grams covered by 1 unit of rapid-acting insulin.
For example, if your total daily dose was 50, the calculation would be as follows: 500 ÷ 50 = 10. This would mean that 10 grams of carbohydrate would require 1 unit of insulin, giving a ratio of 1:10.