12 Understanding PDM and Pod Function
Bolus Calculator equations
The Bolus Calculator first calculates a preliminary correction and meal bolus. It
then adjusts these preliminary values for IOB, if applicable. The final suggested
bolus is equal to the sum of the resulting correction bolus and meal bolus.
Preliminary correction bolus = Current BG - Target BG
Example: Current BG: 11.2 mmol/L, Target BG: 5.6 mmol/L
Correction Factor (CF): 2.8
11.2 mmol/L – 5.6 mmol/L = 2 U prelim. correction bolus
2.8
Preliminary meal bolus =
Example: Carb intake: 45 grams of carb, IC ratio: 15
45 = 3 U prelim. meal bolus
15
Final correction bolus = (prelim. correction bolus - meal IOB) - correction IOB
The meal IOB is subtracted first. If the preliminary correction bolus is still
above zero, then the correction IOB is subtracted
Note: A correction bolus is never reduced below 0 U.
Final meal bolus = prelim. meal bolus - remaining correction IOB
Meal IOB is never subtracted from a meal bolus. Only a remaining correction
IOB is subtracted from a meal bolus (see "Remaining correction IOB" on
page 152).
Note: A meal bolus is never reduced below 0 U.
Calculated bolus = final correction bolus + final meal bolus
Reverse Correction bolus calculation: If the Reverse Correction feature is turned
on and if your current blood glucose is below your Target BG but above your
Minimum BG for Calcs, the Bolus Calculator subtracts a correction amount from
the preliminary meal bolus.
Meal bolus with Reverse Correction = Reverse Correction + prelim meal bolus
Example: Current BG: 4.2 mmol/L, Target BG: 5.6 mmol/L
Correction Factor: 2.8, Preliminary meal bolus: 1.5 U
4.2 mmol/L – 5.6 mmol/L = -0.5 U Reverse Correction
2.8
- 0.5 U (Reverse Correction) + 1.5 U (prelim meal bolus) = 1.0 U meal bolus
150
Correction Factor
Carb intake
Insulin-to-carb (IC) ratio
Effective Date: 18OCT2020, PCO-000235