Carbs on board (COB)
Also called carbohydrates on board, active carbs.
Carbs on board is an estimate of how many grams of a logged meal have not yet been absorbed. Open-source automated insulin delivery systems such as OpenAPS use it in their glucose forecasts. It is an estimate from the app's model, not a measurement. (OpenAPS documentation)
Worked example
Dinner is logged as 60 g at 6:00 p.m. At 7:00 p.m. the app might estimate 35 g still on board; by 9:00 p.m. the estimate falls toward zero.
Related terms
Sources, quoted
- OpenAPS documentation: “Describes an estimation of how many Carbs are still active in the body.”
- OpenAPS documentation: “COBpredBG - a variable that uses carbs and insulin together in predicting the BG curve.”
Every quote above is checked against its source page before each update of this site; last checked 2026-10-06. The worked example is our own arithmetic. This page explains a term; it is not advice for a person's treatment.