Loop’s algorithm for adjusting insulin delivery is oriented around making a glucose prediction. Every five minutes, triggered by new BG data, it generates a new prediction. Both bolus recommendations and temporary basal rates are set based on this prediction.


This graph and legend illustrates terms commonly used in discussing Loop's algorithm, and shows them in the context of historical and forecasted BG in a style similar to the status screen of Loop.

Chart illustrating terms

Insulin Action Duration
A configuration value that provides an estimate of how long insulin stays active after delivery.
Correction Range
This is the low and high BG values that Loop will attempt to keep you between.
Predicted Glucose
Loop makes a prediction of glucose values out for a length of time equal to your Insulin Action Duration.
Eventual BG
The last value of the prediction.
Minimum BG
The lowest glucose value at any point in time within the prediction.
Suspend Threshold
A configuration value below which Loop will suspend all insulin delivery.
CGM Data
Actual glucose measurements made by a continuous glucose monitor.
Insulin Sensitivity
A configuration value that provides an estimate of how much blood glucose will drop given a unit of insulin.